I don't think it's that easy, if you dig deep enough you'll find that they're based on older religions, which are based on even older ones...
"Faith", "believers" - I don't about other religions, but go ask catholic priest if his religion is "right" and I think majority will answer you that it's what they believe & hope is right, but there is no certainty.
But there is one certain thing - it's God is more like Old Testament/ Quran One than New Testament then we're all fucked, because to follow all of His orders in almost impossible, even for orthodox believers.
PS Is Buddhism a religion? I heard is more like way of living which you can follow regardless of your religion
