The paganisn in Christianity indeed DOES come from Mizraim (Egypt), as well as Lybia, Cush, etc. Nimrod(from Ham) had GREAT influence over the other tribes, and yes idolitry leaked into the chosen ones. All you have to do is read any part of the OT to see this. As for Christianity- Catholicism GLADLY enveloped this pagan edict, as did the psuedo-christian groups (masons, rosicrucians, templars, etc).
But Christianity is NEW and INDEED A RELIGION- which has nothing to do with "God". The true Faith, that PREDATES Egypt, is the same one that Adam and Khawah (eve) had. Everything else that came later was just that- later.