nailit - in answer to OP (and I have not read any other answers) I can honestly say that there have been several (if not many ) occasions which have made me think that I might well have been wrong and deluded myself.
At various times in my life I have considered myself an agnostic and in private I have wondered about atheism. Much angst has ensued.
It would be hard to list these times, but they have happened. One such would (within the last 5 years) have been the death of Mr. J2's daughter. She had been a nurse, never drank much, never smoked, healthy diet etc.. Bowel cancer got her. It is the wrong way round for a child to die first.
He struggled for some time, but has held his faith, indeed he has emerged stronger - as have I.
Best I can do :)