The singular is striking given the plural at the beginning of this letter (1 Thessalonians 1:1: Paul, Silvanus, and Timothy). It is also surprising that Paul uses the oath formula here. He strongly admonishes his readers to read this letter to all members of the congregation. No one should miss what the apostle writes at the behest of his Lord. Behind Paul stands the Lord Jesus. This underlines the authoritative character of what the apostle writes here. It is also obvious that this letter will be read outside the congregation in Thessalonica (see Colossians 4:16). God’s gospel should be known to many.
27 I put you under oath before the Lord to have this letter read to all the brothers.