They do not know its fake. It is what they call faith that keeps them going. Some become so obsessed with it. But leave them alone. You don't want them to think you are receptive to their teaching(s) and they start their preaching all day and all night, your ears will hurt! They believe in HIM. He is their saviour and lord. He is a rock star to them. And they have a strong sense of Mission to spread their Good News! Keep a safe distance.