The first letter of Apostle Paul to the Thessalonians is the oldest text of the New Testament. It was written about a year after the Apostolic Council of Jerusalem and is addressed to the newly enlightened believers of Thessaloniki, who had recently "turned to God from idols to serve the living and true God". [...]
The publication of this explanatory memo coincides with the celebration by the Thessalonians of the 2300 years since the founding of the city, which is why it is dedicated to the Church of Thessaloniki. [...]

(from the preface of the first edition)