1 Therefore, when we could no longer endure it, we thought it good to be left in Athens alone,
2 and sent Timothy, our brother and minister of God, and our fellow laborer in the gospel of Christ, to establish you and encourage you concerning your faith,
3 that no one should be shaken by these afflictions; for you yourselves know that we are appointed to this.
4 For, in fact, we told you before when we were with you that we would suffer tribulation, just as it happened, and you know.
therefore (v.1) — because of Paul’s affection for them and his (frustrated) desire to see them again (1 Thessalonians 2:17-20).
endure (v.1) = lit.” by covering to keep off” — to bear up against, to hold out against, bear, forbear — Paul could no longer endure the suspense of being away from them while not knowing how they were holding up
we (v.1) — Paul, Timothy, and Silas all loved the Thessalonians and they all though it best for Paul to be left in Athens alone while they went to visit.
alone (v.1) — Acts 17:16 is no contradiction. Verse 16 explains. It was after Paul’s discourse at Mars Hill that Timothy was evidently reunited with him again and then sent back to the Thessalonians. — Stam, page 45.
establish (v.2) = fix firmly, strengthen, support
encourage (v.2) — with the idea of comforting
shaken (v.3) = lit. “to wag the tail” — perturbed, disturb, beguile, agitate, move — Paul wanted to be sure the afflictions wouldn’t move them away from the faith — the opposite of “establish” in v.2.