It only takes one single article of faith to be rejected by any Catholic for him to place himself outside of the Church. How much further from the Arc of Salvation are the 'religions' which teach that Jesus was a mere man, (Mohammedism), or worse yet, teach that He is in Hell, (as the Talmud does)???
If you love the Truth, and if you love your Catholic faith, and if you love Christ, you cannot help but to reject these anti-Christ faiths and all of their teachings. There have been other earlier faiths that mimicked the Catholic faith somewhat, or held some of the same tenets of faith, and they have been condemned by various Catholic Ecumenical Councils. Such as the Cathari, Arianism, and some earlier sects like the Essenians and gnostics. As I said earlier, the truth is whole, entire and complete, or it is not the truth at all. You simply cannot have 'partial truths'. This is like being lost in the desert and having bits and pieces of a map to your destination--- the bits and pieces are true but will avail you nothing whatsoever. Unless you have the whole map the bits and pieces of 'truth' are useless.
As Paul said when speaking of those who refused to believe and convert: "What have I to do with them"?