They went out from us, but they didn't belong to us; for if they had belonged to us, they would have continued with us. But they left, that they might be revealed that none of them belong to us.

 In 2 Thessalonians 2:3-4, Paul speaks of "the man of sin," the one who exalts himself above all that is called God and all that is worshipped and who sets himself up in the very Temple of God. We do not know whom Paul was expecting, but again there is this thought of one who was the incarnation of everything which was opposed to God. 