This letter is apt to be the very first book to be written of the New Testament. The only possible competitor would be the Letter to the Galatians -- if we hold the view that Paul directed it to the communities he founded in South Galatia on his first missionary expedition, in 46-49 A.D. Then Galatians might have been written in 48 B.C. But it is more likely that Paul wrote to North Galatia, to communities he founded on his second expedition, and then the date would probably be about 54 A.D.

This first letter to Thessalonika was written from Corinth, probably early in 51 A.D. Paul had stayed in Thessalonika some time, to judge from the flourishing community there. He seems to have written this letter out of concern for how the Christians there would stand up under the attacks of the Jews. He says he wanted to return, but "Satan hindered us" (2:18). So he sent Timothy to check. Timothy brought a good report, with no mention of serious abuses, such as later developed at Corinth.

The city of Thessalonika had been founded by Cassander, one of the generals of Alexander the Great, in 316 B.C. It became the capital of the new Roman province of Macedonia in 146. In 42 B.C. it backed Octavius against Brutus and Cassius at the battle of Philippi. Since Octavius won, Thessalonika became a free city.

Although some doubt whether Paul wrote certain letters that now bear his name (such as Second Thessalonians, as we shall see), everyone agrees on the authenticity of First Thessalonians.