Idolatrous Christians?

I had an interesting thought while listening to John MacArthur's talks at this address.

If I don't study my Bible, am I guilty of idolatry? Worshiping a false Christ is just as bad as worshiping a false god. No wonder Jesus said he would deny knowing some people who called Him Lord. It wasn't the "real Jesus" they were worshiping, but one that they invented themselves.