There was a thought process going around that basically encouraged people to not do anything because Jesus was coming back soon. Why bother being constructive, helping each other out, working a full day for wages, or doing anything productive. This is a classic example of people hearing what they want to hear in a message. As  the Apostle Paul talks to the people of Thessaloniki he reminds them that they should be working hard and being productive, no lazy or idle because it is in those places that the Devil can do some of his best work.