For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek.
1 Corinthians 1:18For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God.
1 Thessalonians 1:5For 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.