The Jews: Who both killed the Lord Jesus, and their own prophets, and have persecuted us; and they please not God, and are contrary to all men.... The wrath is come upon them to the uttermost. 2:14
Trivia: What prevented Paul from visiting the Thessalonians?
Paul predicts that the Jesus will return in his lifetime. He will descend from heaven, the dead will rise, and believers will meet him in the air. This is the main scriptural basis for the "rapture" although that word is not used in the passage or anywhere else in the Bible. (See Mt 24:40-41 for the other source for the rapture.)