For we do not preach ourselves, but Christ Jesus the Lord, and ourselves your bondservants for Jesus’ sake. For it is the God who commanded light to shine out of darkness, who has shone in our hearts to give the light of the knowledge of the glory of God in the face of Jesus Christ (2 Corinthians 4:5-6 NKJV).

And my speech and my preaching were not with persuasive words of human wisdom, but in demonstration of the Spirit and of power, that your faith should not be in the wisdom of men but in the power of God. (1 Corinthians 2:4-5 NKJV).

If God had not spoken, we would not dare to speak, because we would have nothing to say except our own threadbare speculations. But since God has spoken, we too must speak, communicating to others what he has communicated in Scripture. Indeed, we refuse to be silenced. As Amos put it, "The Lion has roared—who will not fear? The Sovereign Lord has spoken—who can but prophesy?" that is, pass on the Word he has spoken. And similarly, Paul echoing Psalm 116 wrote, "We believe and therefore we speak." That is, we believe what God has spoken, and that is why we also speak. - John Stott