Given that I am a Catholic, I am completely convinced that it is real. Reason alone can tell us that it is, without any appeal to religion. We can know by reason that God exists, that humans have an immortal soul, etc. And by revelation, we know with certainty that angels and demons exist – to say nothing of the testimonies of Catholic exorcists. Let us not forget miracles at places like Lourdes, one of which was witnessed by Nobel Prize winning physician (and agnostic at the time) Alexis Carrell.