Because Paul relies heavily on what he taught the saints while with them, 2 These 2:3-12 is one of the most obscure passages in his epistles. Considering other passages from Paul and the prophetic phrases he borrows from Daniel, it seems he is saying that, before Christ returns, there will be a massive apostasy, led by a final antichrist, who will blaspheme God as he assumes authority in the professing church. The pastoral admonition is to be alert and watchful, grounded in Scripture that we be not deceived.