I think it was because he realised that no man can really know, it’s all just a matter of faith.
Yes, exactly, stuartcr! Ultimately even to believe that reason itself is "reasonable" is an act of faith.
Which then looks for its support and surety in the most truthful source it can find....
Everything we think we know finally rests on a "cause" that cannot be proved by scientific test in principle. Yet without such a cause, there would be no universe, but only formlessness, chaos....
I should just put it in a nutshell this way: Even belief in the powers of the human mind is an act of faith. But, oh, how we do rely on those powers just to get through the day — not to mention, to build a free and just society.
But now I guess I'm really going off-track here. Best to wrap up.
Thank you so very much, stuartcr, for sharing your well-considered (and methinks most insightful) thoughts in these matters!