Libertinism Defined
Sufism is ineffable and as such, can only be communicated by means of symbolic allusion.
Sufi poetry is bacchanalian in nature, using wine for example as a way of alluding to spiritual intoxication. The person who takes symbols literally, whether out of ignorance or malice, is a literalist.
Thus, the libertine is a Sufi literalist. He mistakes a spiritual wine for a worldly wine, convincing himself that he has attained to mystic heights. If you describe a spiritual station to a libertine, he imagines that he has already reached it and more. They delight in telling you how spiritually advanced they are. And the blinder they become, the more they think they see clearly.
Then the spiritual crisis comes. At that point, the realization sets in that they are as ignorant as the beasts. It has all been an illusion. It is at this point that they lose their faith.
There is a natural progression from libertinism to kufr.