I know Brian Zahnd and found his courage here both refreshing and honest:
But am I suggesting that we should engage in an objective study of comparative religions? No. In fact, I think such an undertaking is impossible. Not inadvisable, but literally impossible. You can only experience a religion by being a believer within the faith and practice of that religion. Religion cannot be approached objectively. The very nature of religion prevents this. For example: One can be thoroughly versed in the teachings of the New Testament (a scholar even) and be well acquainted with Christian theology and worship, church history and practice and still not believe. Which is to say it is thoroughly possible to be an expert on Christianity and not be a Christian. Bart Ehrman would be an example. (And Bart Ehrman would agree.) Or to say it another way: I could become an expert on the Koran and Islam, but that alone would not make me a Muslim. Faith is the essence of religion, not empirical knowledge. We cannot study religions like we do insects. Well, we can, but being an expert on grasshoppers does not make you a grasshopper. And being an expert on Hinduism doesn’t make you a Hindu. Religious faith is a subjective experience — not objective empirical knowledge.
Which is to say you don’t know what it means to be a Muslim, Hindu, Buddhist, Jew, Christian…until you are one! And to be one, is to not be the other. So comparison becomes impossible.
The modern, sloppy notion that we can mix-and-match religions like we do pants and socks is utter nonsense. The modern person who says, “I’m a Buddhist-Hindu-Muslim-Christian” is in reality a secularist wearing religious accessories. The truth is they know virtually nothing about what it means to actually be a Buddhist or a Hindu or a Muslim or a Christian.
The nature of religion based in faith makes the comparative religion project ultimately impossible.
To be an adherent of a religion is to believe, and faith is not an object of empirical inquiry.
I believe Jesus is risen from the dead. But I cannot prove it.
(I do believe the resurrection is the most reasonable explanation for the empty tomb and the rise of Christianity, but it cannot be proven.)