Progressive revelation.
183. Progressive revelation is a teaching clearly proclaimed by Bahá’u’lláh in the Bahá’í writings. With this one teaching he clearly proclaims the essential unity of the messengers of God: In the writings of the Bahá’í Faith the concept of progressive revelation is clearly brought into the light. There is one God, mankind is one and the foundations of religion are one; So all the prophets from the world’s great religions were sent here from the one same God to educate all of His children and not just a select few. 
Babi Religion: “The Lord of the universe hath never raised up a prophet nor hath He sent down a Book unless He hath established His covenant with all men, calling for their acceptance of the next Revelation and of the next Book; inasmuch as the outpourings of His bounty are ceaseless and without limit.”
(The Bab, Selections from the Writings of the Bab, p. 85)
BABI RELIGION: “He (The Bab) bade them declare that whoever believes in Him has believed in all the prophets of God, and that whoever denies Him has denied all His saints and His chosen ones.” “I am all the Prophets’, inasmuch as what shineth resplendent in each one of Them hath been and will ever remain the one and the same sun.”
(The Bab, The Dawn-Breakers, and Selections from the Writings of the Bab, pp. 94 and 124)
Progressive revelation, though not openly proclaimed in the older religious writings of the other prophets, is strongly indicated by the functionality and teachings of the previous religions, so it is more or less implied by the other religions of God.
BAHA’I FAITH: “The term progressive revelation is used to denote the continuous number of prophets, or manifestations of God, that have been sent to the earth as divine educators of mankind. The Reality of the divine Religions is one, because the Reality is one and cannot be two. All the prophets are united in their message, and unshaken. They are like the sun; in different seasons they ascend from different rising points on the horizon. Therefore every ancient prophet gave the glad tidings of the future, and every future has accepted the past.”
(Bahá’í Faith, Abdu’l-Baha, Abdu’l-Baha in London, p. 28)
One of the things that clearly stand out when one is studying the Holy Scriptures is the continuing progression of the Holy covenant, or agreement, that God makes with man through His divine manifestations from generation to generation. 
Judaism: Psalms 111:9 “He hath commanded his covenant for ever: holy and reverend is his name.” David is telling us here that God’s covenant with us is forever. Since that is the case, if we are to follow the continuous covenant that God has been making with mankind we can see progressive revelation in action: 
Christianity: Hebrews 13:20 “Now the God of peace, that brought again from the dead our Lord Jesus, that great shepherd of the sheep, through the blood of the everlasting covenant,” we find that God has been sending his divine manifestations in cycles and if we care to look we see the evidence of God‘s progressive revelation by just following the progression of the covenant of God with man:
BAHA’I FAITH: “Today, every wise, vigilant and foresighted person is awakened, and to him are unveiled the mysteries of the future which show that nothing save the power of the Covenant is able to stir and move the heart of humanity, just as the New and Old Testaments propounded throughout all regions the Cause of Christ and were the pulsating power in the body of the human world.”
(Bahá’í Faith, Abdu’l-Baha, Selections from the Writings of Abdu’l-Baha, p. 223)
BABI RELIGION: “With each and every Prophet Whom We have sent down in the past, We have established a separate Covenant concerning the Remembrance of God and His Day.” “The Lord of the universe hath never raised up a prophet nor hath He sent down a Book unless He hath established His covenant with all men, calling for their acceptance of the next Revelation and of the next Book; inasmuch as the outpourings of His bounty are ceaseless and without limit.”
(The Bab, Selections from the Writings of the Bab, pp. 68 and 86)
SABEANISM: A. (Adam) “And it was revealed to me (?) and to all of them in this book, and they acted upon this reliable baser acting according to this (its) light and removing nothing from this writing of great revelation that was given to Adam the first man.” “And Thou hast spoken to us with Thy Word And hast commanded us with Thy commandment ‘Be My glory and I will be your Glory. Be My light and I will be your Light. And My name shall be in your mouths And I will be with you.’ Thou art He who over-throwest (false) gods in their high-places And bringest reproach on the divinity of (false) deities.” This is the agreement (Haiyi, God) made with Adam; His covenant with mankind. (Sabeanism, Ginza Rba- chapter 75)
JUDAISM: B. (Noah) Genesis 6:18 “But with thee will I establish my covenant; and thou shalt come into the ark.”
C. (Abraham) Genesis 15:18 “In the same day the LORD made a covenant with Abram (Abraham), saying, Unto thy seed have I given this land.”
HINDUISM: D. (Krishna) “Freedom from anger, from exultation, from grumbling, from covetousness, from perplexity, from hypocrisy (and) hurtfulness; truthfulness, moderation in eating, silencing a slander, freedom from envy, self-denying liberality, avoiding to accept gifts, uprightness, affability, extinction of the passions, subjection of the senses, peace with all created beings, concentration (of the mind on the contemplation of the Atman), regulation of one’s conduct according to that of the Aryas, peacefulness and contentedness; — these (good qualities) have been settled by the agreement (of the wise) (the covenant) for all (the four) orders; he who, according to the precepts of the sacred law, practices these, enters the universal soul.”
(Hindu, The Dharma Sutras, Apastamba Prasna I, Patala 8, Khanda 23)
JUDAISM: E. (Moses) Exodus 2:24 “And God heard their groaning, and God remembered his covenant with Abraham, with Isaac, and with Jacob.” Exodus 34:28 “And he was there with The LORD forty days and forty nights; he did neither eat bread, nor drink water. And he wrote upon the tables the words of the covenant, the ten commandments.”
ZOROASTRIANISM: F. (Zoroaster, Zarathustra) “And we worship the former religions of the world devoted to Righteousness which were instituted at the creation, the holy religions of the Creator Ahura Mazda (God), the resplendent and glorious.” (The Zend-Avesta, Avesta – Yasna 16)
14. “O Zarathushtra, what righteous man is thy friend for the great covenant?” 19. “He who accomplisheth for Me, even Zarathushtra, in accordance with Right that which best agrees with My will, to him as earning the reward of the Other Life.”
(Zoroaster, The Zend-Avesta, Avesta – Yasna 46)
BUDDHISM: G. (Buddha) “Making the effort is your affair. The Buddhas have pointed out the Way. Those who are on the way and practicing meditation will be freed from Mara’s bonds.” 18. “Make yourself an island; work hard; be wise. When your impurities are purged and you are free from guilt, you will enter into the heavenly world.” (This is the agreement or covenant Brahma, God made with man through The Buddha)
(Buddhist, Dhammapada – Sayings of the Buddha 1 and 2 (tr. J. Richards))
CHRISTIANITY: H. (Jesus Christ) Hebrews 12:24 “And to Jesus the mediator of the new covenant, Hebrews 8:6 “But now hath he obtained a more excellent ministry, by how much also he is the mediator of a better covenant, which was established upon better promises.” Hebrews 8:7 “For if that first covenant had been faultless, then should no place have been sought for the second.”
ISLAM: I. (Muhammad) “And call in remembrance the favor of Allah (God) unto you, and His Covenant, which He ratified with you, when ye said: ‘We hear and we obey’: and fear Allah, for Allah knoweth well the secrets of your hearts” (The Qur’an (Yusuf Ali tr), Surah 5)
7. “And remember We took from the Prophets their Covenant as (We did) from thee: from Noah, Abraham, Moses, and Jesus the son of Mary: We took from them a solemn Covenant:” 67. “For every Message is a limit of time,”
(The Qur’an (Yusuf Ali tr), Surah 6 and 33)
BABI RELIGION: J. (The Bab) “My Covenant with you is now accomplished. Gird up the loins of endeavour, and arise to diffuse My Cause. Be not dismayed at the sight of the degeneracy and perversity of this generation, for The Lord of the Covenant shall assuredly assist you. Verily, He shall surround you with His loving protection, and shall lead you from victory to victory.”
The Bab: (Shoghi Effendi, The Dawn-Breakers, p. 85)
BAHA’I FAITH: K. (Baha’u’llah) “His Holiness Christ made a covenant concerning the Paraclete (Comforter or helper, the Holy Ghost) and gave the tidings of His coming. His Holiness the Prophet Muhammad made a covenant concerning His Holiness the Bab and the Bab was the One promised by Muhammad, for Muhammad gave the tidings of His coming. The Bab made a Covenant concerning the Blessed Beauty of Bahá’u’lláh and gave the glad-tidings of His coming for the Blessed Beauty was the One promised by His Holiness the Bab. Bahá’u’lláh made a covenant concerning a promised One who will become manifest after one thousand or thousands of years. He likewise, with His Supreme Pen, entered into a great Covenant and Testament with all the Bahá’ís whereby they were all commanded to follow the Center of the Covenant (Abdu’l-Baha) after His departure, and turn not away even to a hair’s breadth from obeying Him.”
(Bahá’í Faith, Abdu’l-Baha, Baha’i World Faith – Abdu’l-Baha Section, p. 358)
The covenant God has made with man may be everlasting, but it is like a living thing. It is a continuing process that occasionally needs to be renewed or, we might say, upgraded as mankind matures and develops both mentally, spiritually and socially.
BAHA’I FAITH: “Religion is the outer expression of the divine reality. Therefore it must be living, vitalized, moving and progressive.” “As we develop, as a race, we change and grow in our thinking and in the way we do things.” “The power of the Covenant is able to stir and move the heart of humanity, just as the New and Old Testaments propounded throughout all regions the Cause of Christ and were the pulsating power in the body of the human world.” “The Covenant of God is like unto a vast and fathomless ocean.”
(Abdu’l-Baha, Baha’i World Faith p. 224 and Selections from the Writings of Abdu’l-Baha, p. 223)
JUDAISM: Ezra 6:38 “And I said, O Lord, Thou spakest from the beginning of the creation,” “by the mouth of His holy prophets.” (Deuterocanonical Apocrypha, Esdras 2 (Ezra 4) Luke 1:70)
CHRISTIANITY: Luke 1:70 “He (God) spake by the mouth of His holy prophets, which have been since the world began:” Acts 3:21 “God hath spoken by the mouth of all His holy prophets since the world began.”
ISLAM: 136. “We believe in Allah (God), and the revelation given to us, and to Abraham, Isma’il, Isaac, Jacob, and the Tribes, and that given to Moses and Jesus and that given to (all) Prophets from their Lord, we make no difference between one and another of them, and we bow to Allah (in Islam).” 3. “It is He Who sent down to thee (step by step), in truth, the Book, confirming what went before it; and He sent down Law (of Moses) and the Gospel (of Jesus) before this, as a guide to mankind, and He sent down the Criterion (of judgment between right and wrong).” “144. “Muhammad is no more than a Messenger: many were the Messengers that passed away before him.”
(The Qur’an (Yusuf Ali tr), Surahs 2 and 3)
Islam: 196. “For my protector is Allah, Who revealed the Book (from time to time), and He will choose and befriend the righteous.” 101. “When We substitute one revelation for another, and Allah knows best what He reveals (in stages), they say, “Thou art but a forger”: but most of them understand not.” 102. “Say, the Holy Spirit has brought the revelation from thy Lord in truth, in order to strengthen those who believe, and as a guide and Glad Tidings.” 36. “For We assuredly sent amongst every People a Messenger, (with the Command), ‘Serve Allah and eschew Evil:’ of the people were some whom Allah guided, and some on whom Error became inevitably (established). So travel through the earth, and see what was the end of those who denied (the Truth).”
(The Qur’an (Yusuf Ali tr), Surahs 7 and 16)
Islam: 23. “Allah has revealed (from time to time) the most beautiful Message in the form of a Book, consistent with itself, (yet) repeating (its teaching in various aspects).” 106. “None of Our revelations do We abrogate or cause to be forgotten, but We substitute something better or similar; knowest thou not that Allah hath power over all things? Knowest thou not that to Allah belongeth the dominion of the heavens and the earth! And besides Him ye have neither patron nor helper.”
(The Qur’an (Yusuf Ali tr), Surahs 2 and 39)
Islam: “Let every nation follow what they used to worship, and now we are waiting for our Lord.’ Then the Almighty will come to them in a shape other than the one which they saw the first time, and He will say, ‘I am your Lord,’ and they will say, ‘You are not our Lord.”’ They will be blind to the new manifestation of God, Allah will send them. They have eyes to see, but don’t see the true light of Allah when it dawns, and fail to hear the truth of His words. 13. “The same religion has He established for you as that which He enjoined on Noah-the which We have sent by inspiration to thee-and that which We enjoined on Abraham, Moses, and Jesus: Namely, that ye should remain steadfast in Religion, and make no divisions therein: to those who worship other things than Allah, hard is the (way) to which thou callest them. Allah chooses to Himself those whom He pleases, and guides to Himself those who turn (to Him).”
(The Qur’an (Yusuf Ali tr), Surah 42 and Hadith, Bukhari Vol 9, Book 93, # 532)
ZOROASTRIANISM: 3. “And we worship the former religions of the world devoted to Righteousness which were instituted at the creation, the holy religions of the Creator Ahura Mazda (God), the resplendent and glorious.” 2. “If by reason of these things the better path is not in sight for choosing, then will I come to you all as judge of the parties twain whom Ahura Mazda knoweth, that we may live according to the Right.”
(Zoroaster, The Zend-Avesta, Avesta – Yasnas 16 and 31)
Zoroastrianism: 3. “When, Mazda, shall the sun risings come forth for the worlds winning of Right, through the powerful teachings of the wisdom of the future Deliverers (future prophets)? Who are they to whose help Good Thought shall come? I have faith that thou wilt thyself fulfill this for me, O Ahura.”
(The Zend-Avesta, Avesta – Yasna 46)
Zoroastrianism: “The busy world is apt to forget the most important lesson of life so the merciful Mazda sends prophets now and then to remind men of their highest destiny.” (ZOROASTER, Hymns of Atharvan)
Zoroastrianism: “The path, O Ahura, which You told me to be of conscience, and which happens to be the religion of all the prophets, and which, by good deeds promotes rectitude as well, and which brings to the righteous recompense of which You are the giver; the way of all the saints (saoshyants) may be said to be only one. For in essential matters, there is no difference between one prophet and another. In as much as the same God is worshipped everywhere. All of them are different phases of the same religion.” (ZOROASTER, Hymns of Atharvan pp. 314 thru 316)
HINDUISM: “I come, and go, and come. When Righteousness Declines, O Bharata! when Wickedness Is strong, I rise, from age to age, and take Visible shape, and move a man with men, Succouring the good, thrusting the evil back, And setting Virtue on her seat again.”
(Hindu, Bhagavad Gita (Edwin Arnold tr) chapter 4)
Hinduism: “As I before have been So will I be again for thee; with lightened heart behold! Once more I am thy Krishna, the form thou knew’st of old!”
(Hindu, Bhagavad Gita (Edwin Arnold tr) chapter 9)
BUDDHISM: “All Buddhas past, present and future having obtained Highest Samadhi awake to find themselves realizing Parjna-Paramita (transcendent truth). Therefore everyone should seek the self realization of Parjna-Paramita the unsurpassable truth that ends all pain, that spans the troubled ocean of life and death safely carrying all to the other shore of enlightenment.” (Buddha, Parjna Paramita)
Buddhism: “I am not the first Buddha who came upon earth, nor shall I be the last. In due time another Buddha will arise…. He shall reveal to you the same eternal truths which I have taught you. He will preach to you His religion, glorious in its origin, glorious at the climax and glorious at the goal, in the spirit and in the letter.” [Sermon of the Great Passing.]
SABEANISM: “In the Name of The Great Life (Haiyi, God). Vines shone in the water And in the Jordan mighty they grew. Ye are flourishing offshoots. Messengers hither I bring you.” “Establishing Your likeness and giving us light, Let your radiance shine upon us.” (Sabeanism, Ginza Rba- chapters 177 and 382)
BABI RELIGION: “FEAR ye God and breathe not a word concerning His Most Great Remembrance other than what hath been ordained by God, inasmuch as We have established a separate covenant regarding Him with every Prophet and His followers. Indeed, We have not sent any Messenger without this binding covenant.” “Verily He doth exercise undisputed authority over His revelations unto all mankind.”
(The Bab, Selections from the Writings of the Bab, pp. 33 and 45)
BAHA’I FAITH: “The great ones are from all time in their glorious station, their reality is luminous from the beginning, the reality that causes the qualities of God to appear, but the day of their manifestation is the day when they proclaim themselves of this earth.”
(Bahá’í Faith, Abdu’l-Baha, Divine Philosophy, p. 52)
Baha’i Faith: “From the days of Adam until today, the religions of God have been made manifest, one following the other, and each one of them fulfilled its due function, revived mankind, and provided education and enlightenment. They freed the people from the darkness of the world of nature and ushered them into the brightness of the Kingdom. As each succeeding Faith and Law became revealed it remained for some centuries a richly fruitful tree and to it was committed the happiness of humankind. However, as the centuries rolled by, it aged, it flourished no more and put forth no fruit, wherefore was it then made young again.”
“The religion of God is one religion, but it must ever be renewed. Moses, for example, was sent forth to man and He established a Law, and the Children of Israel, through that Mosaic Law, were delivered out of their ignorance and came into the light; they were lifted up from their abjectness and attained to a glory that fadeth not. Still, as the long years wore on, that radiance passed by, that splendour set, that bright day turned to night; and once that night grew triply dark, the star of the Messiah dawned, so that again a glory lit the world.”
(Bahá’í Faith, Abdu’l-Baha, Selections from the Writings of Abdu’l-Baha, p. 51)