Def at odds with true Christianity but subtle enough for some not to question it.
Satan is a wonderful seducer, to be sure.
Syncretism. The art of blending some poisonous deception into the life of the church as if it was just some compatible new way of thinking. That’s how Gnosticism wormed its way into the early church and that’s why John had such a vehemence against it when it first raised its ugly head.
I say the same thing about Catholicism.