Baha'is acknowledge there can be Manifestations that are unknown to us...Robert Stockman a Baha'i scholar refers to this:
Bahá'u'lláh makes it clear that divine revelation has not been confined to a particular period of human history. Rather, He states that "the Manifestations of His Divine Glory. . . have been sent down from time immemorial, and been commissioned to summon mankind to the one true God. That the names of some of them are forgotten and the records of their lives lost is to be attributed to the disturbances and changes that have overtaken the world" (
Gleanings from the Writings of Bahá'u'lláh, 174). This statement is important because it makes it clear that religions other than the ones possessing known Manifestations may have been divinely established. In addition to the historic figures already listed, Bahá'u'lláh mentions Húd and Sálih--legendary figures who appeared to Arab tribes, and who are also mentioned in the Qur'án--as Manifestations. They may be seen as examples of Manifestations to
primal religions, as the religions of the tribal peoples of the world are often called by religious scholars. While Bahá'u'lláh was not asked about other Manifestations, such as to the African, Chinese, native American, and ancient Indo-European peoples, it is reasonable to assume, based on Bahá'u'lláh's statement above, that Manifestations came to them as well. Based on a statement of 'Abdu'l-Bahá that "in cycles gone by. . . continents remained widely divided, nay even among the people of one and the same continent association and interchange of thought were wellnigh impossible" (
Selections from the Writings of 'Abdu'l-Bahá, 31) the Research Department of the Universal House of Justice has concluded that "it would appear possible that Manifestations of God have lived simultaneously in different areas of the globe" (Research Department memorandum to the Universal House of Justice titled "Questions Relayed by the Spiritual Assembly of Mitcham," dated 24 May 1988).
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Progressive Revelation