1 Thessalonians 1:4-5 Knowing, brethren beloved, your election of God. (5) For our gospel came not unto you in word only, but also in power, and in the Holy Ghost, and in much assurance; as ye know what manner of men we were among you for your sake.
The Believers Bible Commentary says, "The apostle was assured that these saints had been chosen by God before the foundation of the world. But how did he know? Did he have some supernatural insight? No, he knew they were among the elect by the way they had received the gospel.
Note v. 5: By our gospel Paul does not imply a different message from that of the other apostles. The contents were the same; the difference was in the messengers. The Thessalonians had not treated the message as a mere religious lecture; they had, of course, received it in word, but not in word only.
It was in power, and in the Holy Spirit, and in much assurance that it came to them: (1) In power. The message worked in their lives with supernatural energy, producing conviction of sin, repentance, and conversion. (2) In the Holy Spirit. This power was produced by the Holy Spirit. (3) In much assurance. Paul preached with great confidence in the message. The Thessalonians accepted it with much assurance as the word of God. The result in their lives was full assurance of faith.