When one is not grounded in truth (and isn't even seeking it anyway), it is easy for them to be persuaded to believe in anything... One does not need to be held accountable for anything, at least in their mind, if they simply deny the divinity of Christ and the authority of God. It's easy to escape by simply throwing out the "organized religion" card.
This disease of relativism is seen often, even in Christian circles. One excuses their sinful behavior, instead of taking ownership of it, by making statements like, "God and I have an understanding... " or "I don't really think that is what the Bible says... " Absurd.
Truth is truth... and if you're not grounded in it, you will be "blown here and there by every wind of teaching and by the cunning and craftiness of men in their deceitful scheming." (Eph 4:14)