Matthew 3-4 tells us the story of Jesus getting baptized then Jesus being led by
the Spirit into the desert to be tempted by the devil. The main point of these
stories is to remind believers that we are at war. There is a real enemy; if there
is a real enemy, it helps to be mindful of the typical weapons of the enemy as
well as practical methods of fighting back against the evil in the world.
The church at Thessalonica was freaked out about the end of days. Paul assures them of the return of Christ and then prepares them to live in the reality of His return.