If Judaism and Christianity are real religions, what are the fake ones? Did you mean, say, Scientology and neopaganism? Or did you mean, say, other major world religions?
All 'fake' religions are (in reality) some kind of auto-idolatry (let it be violence, egocentrism, and so on, it's a never-ending list...)
But we can't always (by ourselves) distinguish between gratification (read: elevating growth) and egoism (destructive growth).
So we need some 'illumination', which is, in another term: Religion.