Why would mainstream Christians have any need to learn other religions? Since Christianity is an off shoot of Judaism, it has been around a lot longer than you think, in fact longer than the religions you speak of. You, my friend, could stand to learn more about that because is it painfully obvious you have no idea. You probably have no idea that Jesus was present before the Earth was even formed. But you didn't know that, did you?You so-called Christians have a hell of a lot to learn about the religions of the world and so many could benefit from it. Many were created well before Christianity and are still practiced tody. You are so closed-minded in thinking Christianity alone is the only path to Heaven.
The same God that the Hebrews followed is the exact same God the Christians follow today. So, if you examine it correctly, nothing has changed since the beginning except who was brought into the fold.
When it comes to the thinking of Jesus being the only way to heaven, for Christians that is a fact. You can't change what Jesus said. You can argue until the cows come home that other religions say different. That is fine, if you follow them. If we both stand in front of many paths to a destination and I tell you, only one will truly get you there while the others are dead ends and you refuse to accept that and follow the wrong one, who's fault is that? You were warned.
Why not learn more about the religion you DON'T understand? Then you could rightfully argue you points.