No reason justifies disbelief.

[possibletarian]

the missing piece of the puzzle for you to move from unbelief to belief ?

Difficult metaphysical issues don't strike me as the kind of thing you can make a conclusion about after a single book or lecture. It isn't like viewing a single persuasive syllogism, after which you either accept it or not. 

Remember that moment in the Purgatorio, where the angel is piloting the boat? There are some translation issues there, and it's not clear whether the angel is meant to be too bright to see or too perfect. This symbol, the 20th time or so that I read it, brought home to me important understandings of what Plato's Ideal world is thought to be like. This is not coincidental, of course, Dante was a great genius and wrote the book to teach things in just this way. The fact that I had also read Plato a dozen times and didn't deeply grok that element about ideality made it clear that it isn't a lack of "pieces," necessarily, but a sufficiently deep understanding. 

This is partly what Blake means when he says that the infinity of the world is always present with us, but our senses are closed to it. 

Perhaps people feel I should go about things differently. I get enormous pleasure from my studies, and it has never occurred to me that it was bad to say "I'm not sure yet."

Of course it isn't bad to say ''I'm not sure yet'' in fact if you are not sure it's the only honest thing to say.