From "Wittgenstein on God and Belief" from The Bully Pulpit.
“A proof of God’s existence ought really to be something by means of which one could convince oneself that God exists. But I think that what believers who have furnished such proofs have wanted to do is give their ‘belief’ an intellectual analysis and foundation, although they themselves would never have come to believe as a result of such proofs. Perhaps one could ‘convince someone that God exists’ by means of a certain kind of upbringing, by shaping his life in such a way. Life can educate one to a belief in God."
Wittgenstein held that religion was a practice that would be justified through the form of life of which it was part. This resonates with the central premise of Alain de Botton's recent popular exploration in Religion for Atheists: A Non-Believer's Guide to the Uses of Religion. In short, it is unfair to judge religion based on the factual basis of its beliefs. Instead, one should curiously explore how a certain belief structure gives rise to a form of life. It is - then - that one can - perhaps - be permitted to judge.