Because of this, God sends them a working of error, that they should believe a lie;
The Thessalonians knew what Paul was talking about, because he had given teaching on these things while among them (5). They also knew what we do not, namely, what or who it is that prevents these things from happening now. One suggestion is that this restraining power is the system of law and government that to some extent can control evil in human society (cf. Romans 13:3-4). Evil is always at work in the world, but when the restraining power is removed, evil will reign unhindered till it reaches its fulness in the man of lawlessness. Then Christ will return and with terrible ease destroy him (6-8).