1 Thessalonians 3:2

He calls him also a minister of God. Note, Ministers of the gospel of Christ are ministers of God, to promote the kingdom of God among men. He calls him also his fellow-labourer in the gospel of Christ.

Paul had converted them to the Christian faith, and now he was desirous that they might be confirmed and comforted, that they might confirmed in the choice they had made of the Christian religion, and comforted in the profession and practice of it.

Timotheus, our brother - It appears that Timothy was but a youth when converted to God; he had now however been some years in the work of God; Paul therefore calls him his brother, being one of the same Christian family, a son of God by adoption: elsewhere he calls him his own son, 1Ti 1:2; and his dearly beloved son, 2Ti 1:2; because he was brought to the knowledge of the true God, and to salvation by Christ, through the apostle’s instrumentality. See the preface to the First Epistle to Timothy.

"Gospel ministers do the work of God with Him, for Him, and under Him" [EDMUNDS]. establish--Greek, "confirm." In 2Th 3:3, GOD is said to "stablish": He is the true establisher: ministers are His "instruments." concerning--Greek, "in behalf of," that is, for the furtherance of your faith.

And sent Timotheus - That is, evidently, he sent him from Athens - for this is the fair construction of the passage. But in the history Acts 17 there is no mention that Timothy came to Athens at all, and it may be asked how this statement is reconcilable with the record in the Acts ? It is mentioned there that “the brethren sent away Paul (from Berea) to go, as it were, to the sea: but Silas and Timotheus abode there still. And they that conducted Paul brought him to Athens;” Act 17:14-15. The history further states, that after Paul had remained some time at Athens, he went to Corinth, where he was joined by Timothy and Silas, who came to him “from Macedonia;” Act 18:5. But in order to reconcile the account in the Acts with the statement before us in the Epistle, it is necessary to suppose that Timothy had come to Athens. In reconciling these accounts, we may observe, that though the history does not expressly mention the arrival of Timothy at Athens, yet there are circumstances mentioned which render this extremely probable. First, as soon as Paul reached Athens, he sent a message back to Silas and Timothy to come to him as soon as possible, and there is every probability that this request would be obeyed; Act 17:15. Secondly, his stay at Athens was on purpose that they might join him there. “Now while Paul waited for them at Athens, his spirit was stirred within him;” Act 17:16. Thirdly, his departure from Athens does not appear to have been in any sort hastened or abrupt. He had an opportunity of seeing the city Act 17:23; he disputed in the synagogue and in the market “daily” Act 17:17; he held a controversy with the philosophers Act 17:18-22; he made converts there Act 17:24, and “after these things” he calmly went to Corinth. There was no tumult or excitement, and it is not suggested that he was driven away, as in other places, because his life was in danger. […]