1 Corinthians 2:4

1 Corinthians 1:17 NIV
For Christ did not send me to baptize, but to preach the gospel—not with wisdom and eloquence, lest the cross of Christ be emptied of its power.

1 Corinthians 4:20 NIV
For the kingdom of God is not a matter of talk but of power.

1 Thessalonians 1:5 NIV
because our gospel came to you not simply with words but also with power, with the Holy Spirit and deep conviction. You know how we lived among you for your sake.

Romans 15:19 NIV
by the power of signs and wonders, through the power of the Spirit of God. So from Jerusalem all the way around to Illyricum, I have fully proclaimed the gospel of Christ.