5because 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.
The phrase in the Holy Spirit indicates that the exercise of this power was the particular work of the Holy Spirit, the Third Person of the Trinity. The work of the Spirit by which he enables people to accept the things revealed in the gospel is further explained in 1 Corinthians 2:6–16.
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.