Only went as far as Wikipedia, which referred to an article in the NY Times that claimed his book on his conversion was written by someone else.
I've watched clips in which he discusses his conversion and the reasons for it, so even if his book was
written by someone else (which is not at all unusual at that age, that is, having someone assist you in the more laborious parts of the process), it is not the main or only source of evidence for his conversion.
But the main impetus was my fabulous pun, which you ignored.
And I am a great lover of puns, but unfortunately, my potential enjoyment of that (admittedly nice) one was mitigated by the suggestion that theists have defective brains.