“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.”
King James Version (KJV)
1:5 With power - Piercing the very heart with a sense of sin and deeply convincing you of your want of a Saviour from guilt, misery, and eternal ruin. With the Holy Ghost - Bearing an outward testimony, by miracles, to the truth of what we preached, and you felt: also by his descent through laying on of hands. With much assurance - Literally, with full assurance, and much of it: the Spirit bearing witness by shedding the love of God abroad in your hearts, which is the highest testimony that can be given. And these signs, if not the miraculous gifts, always attend the preaching of the gospel, unless it be in vain: neither are the extraordinary operations of the Holy Ghost ever wholly withheld, where the gospel is preached with power, and men are alive to God. For your sake - Seeking your advantage, not our own.
1Th 1:5 For our gospel came not unto you in word only. God gave the spoken word power, the power of the Holy Spirit which dictated it. But also in power. Observe that the "power" is referred to the preachers. Ye know what manner of men we were among you for your sake. Ye know what was the life, the earnestness and the power of the Holy Spirit of us while we were preaching among you.