2 Thessalonians 2:3-4

v3a: There are many ways in which we can be deceived by false teachers. "Some deceivers will claim new revelations, others will misinterpret Scripture, and others will be guilty of gross counterfeit; people will use various kinds and means of deceit, but we must be careful that no one deceives us in any way."

v3b: Before the return of Christ, there will be "a general apostasy" which is the falling away from "sound teaching, instituted worship and church government, and a holy life" by believers.  From this time of apostasy, the antichrist or man of lawlessness will be revealed.

v4: The antichrist is a man of lawlessness because "he not only is devoted to and practices evil himself; he also promotes, supports, and commands sin and evil in others."  He will oppose and exalt himself above God by demanding obedience to his commands and worship by the church.