I don’t see any value in discussing “credentials” or certification. It’s not your acceptance that I seek either. Seeking to discuss me the person rather than the arguments and views that I espouse is all that should matter here. Insofar as certification goes, I think Prof. Noam Chomsky says it best:
“In my own professional work I have touched on a variety of different fields. I’ve done my work in mathematical linguistics, for example, without any professional credentials in mathematics; in this subject I am completely self-taught, and not very well taught. But I’ve often been invited by universities to speak on mathematical linguistics at mathematics seminars and colloquia. No one has ever asked me whether I have the appropriate credentials to speak on these subjects; the mathematicians couldn’t care less. What they want to know is what I have to say. No one has ever objected to my right to speak, asking whether I have a doctor’s degree in mathematics, or whether I have taken advanced courses in the subject. That would never have entered their minds. They want to know whether I am right or wrong, whether the subject is interesting or not, whether better approaches are possible—the discussion dealt with the subject, not with my right to discuss it.”