No eselam I am afraid you did not answer my question. I did not ask about someone who has "strong faith". When you say this of course you actually mean "strong faith in Islam". Obviously, a person who has strong faith in Islam will not doubt the statement "Allah is the real god and Muhammad the true messenger", but someone with strong faith in Buddhism will doubt it. Anyway, I asked if a righteous, thoughtful, sincere person, using reason and weighing the evidence, has ever doubted this statement.
Let me make the argument a different way. You gave the example of Imam Bukhari who collected sayings of Muhammad. He didn't know, when he started his investigations, which sayings were authentic. So he had to rely on his reason and the evidence, and his knowledge, to judge the authenticity of the sayings he found, to the best of his ability. If he mistakenly judged a hadith incorrectly, could he be blamed? No. Should he have started his investigation by having faith in every hadith he found, and never doubting any of them? Of course not. If reason and evidence, and his best judgment, suggested that a hadith was weak or inauthentic, should Imam Bukhari have assumed this was the devil tempting him? No, because then he would not be able to separate the weak hadiths from the strong ones.
I am basing this off of what you said about Imam Bukhari .... do you agree with what I have said so fair about Imam Bukhari?