Third Basic Baha'i Principle is:
"The Foundation of all Religions is One."
Each Revelator has given the same "New Heaven and Earth," but man has polluted and misrepresented these Divine Laws. In reality they are all one. The third foundation stone, the chalcedony, is pure white, of which 'Abdu'l-Baha said: "While white is apparent, yet in it is hidden and concealed the seven colors. In white all colors are brothers and sisters." White is the symbol of purity, and in its origin each religion is pure, and a brother to every other religion, for all truth is one.
There is only one Religion.
There is but one GOD, by whatever name HE is called. There is but one human race. There can be but one religion. But this one religion has many Speakers, and many expressions.
The life and progress of man are dependent upon the Word of God. In past times the Human race was divided by oceans, mountain ranges, forests, deserts, all the physical barriers which modern inventions have succeeded in surmounting. This is one reason why there have been many Revealers of the Word of God, so that all mankind should receive it.
Baha'u'llah teaches that revelation is progressive, and that each manifestation of God answers the need of his time. This need has two voices. One, crying for spiritual food, satisfaction of the inner life, "knowledge of God", Faith, is always answered in the same way, through spiritual teachings, an outpouring of love, and a renewal of the Soul's vigor. The other voice cries for laws to regulate excesses, abrogation of outworn customs, and organization of daily affairs. Both cries are answered.
"Know of a certainty that in every Dispensation the light of Divine Revelation has been vouchsafed to men in direct proportion to their spiritual capacity. Consider the sun. How feeble its rays the moment it appeareth above the horizon. How gradually its warmth and potency increases as it approaches its zenith, enabling meanwhile all created things to adapt themselves to the growing intensity of its light. How steadily it declines until it reaches its setting point. Were it all of a sudden to manifest the energies within it, it would no doubt cause injury to all created things.... In like manner, if the Sun of Truth were suddenly to reveal, at the earliest stages of its manifestation, the full measure of the potencies which the providence of the Almighty hath bestowed upon it, the earth of human understanding would waste away and be consumed; for men's hearts would neither sustain the intensity of the revelation, nor be able to mirror forth the radiance of its light. Dismayed and overpowered, they would cease to exist."
The true educator of man is the Founder of Religion, who trains him in morals and the higher virtues and reveals to him his spiritual reality. All the Prophets have served this purpose. They have trained men in honesty, truthfulness, trustworthiness, reverence, modesty, civil obedience and self-sacrifice for others. The essential teaching of all Religions the same.
In time, religion becomes corrupt, it loses its early vigor and degenerates into institutions with no spiritual force to energize the inner life of man. Therefore it must be renewed and purified. This is accomplished through the influence of a Messiah, another Speaker.
Man, through successive seasons of civilization and decline, grows in understanding and social capacity. He therefore needs, from time to time, a further measure of that essential, real truth which is both the food of his spirit and the energy of new civilization. This truth is revealed by a Divine Aessenger. Bahá'u'lláh teaches, that religious revelation is progressive, that old forms and institutions must give way to new ones, that revelation is according to the need and capacity of the time.
Jesus the Christ also supports these teachings, religious revelation is according to the capacity and the need. 'I have yet many things to say unto you, but ye cannot bear them now. Howbeit when He, the Spirit of Truth, is come, He will guide you into all truth." "You cannot bear it now.' Jesus not only kept the full intensity of God's Revelation from them, but as well spoke the name of a successor, i.e., "The Spirit of Truth", is one of the many literal English expressions to say, 'Baha'u'llah'.
The names of the Speakers are different. They apply spiritual truth differently to different conditions, and that is a great source of annoyance to conventional minds. The differences in religion are due to the different requirements of the times in which each revelation was made, and the enmity between religions is due to prejudice and ignorance.
"Know thou assuredly that the essence of all the Prophets is one and the same. Their unity is absolute. God, the Creator saith: There is no distinction whatsoever among the Bearers of My Message. They all have but one purpose; their secret is the same secret."
"It is clear and evident, therefore, that any apparent variation in the intensity of their light is not inherent in the light itself, but should rather be attributed to the varying receptivity of an ever-changing world. Every Prophet whom the Almighty and Peerless Creator hath purposed to send to the peoples of the earth hath been entrusted with a Message, and charged to act in a manner that would best meet the requirements of the age in which he appeared. "
Religion is of one common foundation, it comes from God. His messengers speak the same words of unity, harmony and oneness. The Progressive Revelation brought by the Prophets of God, is but the progression of the spiritual evolution and education of mankind's soul, to bring him closer, back unto the pathway of his Creator. There is but one God, there is but one Word, and one Message for mankind.