The fundamental principle enunciated by Baha'u'llah, the followers of His Faith firmly believe, is that religious truth is not absolute but relative, that Divine Revelation is a continuous and progressive process, that all the great religions of the world are divine in origin, that their basic principles are in complete harmony, that their aims and purposes are one and the same, that their teachings are but facets of one truth, that their functions are complementary, that they differ only in the nonessential aspects of their doctrines, and that their missions represent successive stages in the spiritual evolution of human society.

Baha'is believe that religion is a progressive revelation of God. Progressive revelation is a succession of divine revelations from God through His Manifestations. Each Messenger or revelation is the fulfillment of the one before and it prepares a way for the Message which follows. The gradual education and spiritual development of mankind is the result of progressive revelations from God. A simple example of this method of education is the progress of a student in a graded school.These divine teachers have come about every 1000 years, more or less, to teach different peoples living in different parts of the world.No one of the Manifestations of God is to be preferred over any other.All have the same purpose and same divine authority and power. Each one speaks with the Voice of God to the people of His time.But, the Message brought by each succeeding Manifestation of God becomes greater as the understanding of man increases. Each Manifestation of God recognizes the divine station of the Manifestation who came before Him and prophesizes of the coming of another One after Him.