Oh, which do I mean? How do you become a Bahá'í? or, How did that Bahá'í thing come about?
To the question of how did this come about, your asking a question with a very long and involved answer.
The things that happened around the Deceleration of Bahá'u'lláh are intense and involved, to much so to give a short answer with any real meaning, however some people have made attempts. The Introduction to Gleanings from the Writing's of Bahá'u'lláh is pretty good.
As to the question of How do I become a Bahá'i? The answer is simple. Find the Bahái's near your community and talk to them. There a many things that need to be learned, but what simply makes a Bahái is the belief that Bahá'u'lláh is the Manifestation of God for This Day.
Bahá'í National Center
Wilmette, Illinois 60091
If your not in the USA, the Faith has a significant presence in 205 sovereign countries and
dependent territories. Keep looking I'm sure you'll find someone.
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