Knowing Brethren, Beloved, Your Election of God

Paul left the Thessalonians in the midst of heavy persecution. We understand the timing of this letter because we know Paul was concerned about them while in Athens and sent Timothy to check on them in 1Th 3:1-2. In 1Th 3:6, Timothy returns, an event that takes place while Paul has moved on to Corinth in Act 18:1-5. So, this letter comes while he's in Corinth AFTER hearing of their state from Timothy.