1 Thessalonians 1:5
...because our gospel came to you not only in word, but also in power and in the Holy Spirit and with full conviction. You know what kind of men we proved to be among you for your sake.

Yet it is also worth noting that Paul appeals to the character he displayed while he was with the Thessalonians. Not only was his message clear, but his motives were pure, and his methods left nothing to be condemned. Paul did not abuse his position as a minister of the gospel, nor did he seek to be elevated to a lofty pedestal of apostleship. In the core of his being, Paul knew that his message was not about him at all. He was serving as an "ambassador of Christ" [2 Corinthians 5:16-20].

Paul remembered a time in his life, as many of us can likewise recall, when our hearts were set against God. We lived in a way that sought only to please ourselves, never giving the slightest consideration to the work or word of Jesus Christ. How wonderful it is to know that while we were yet sinners, Christ died for us! He did what we could not do, and because of His gracious substitution for us on the cross, we are now offered forgiveness for and removal of our sin.