Earlier in his letter Paul wrote that the Lord will bring to light the things now hidden in darkness and will disclose the purposes of the heart
(1 Corinthians 4:5). There he was referring to what will happen on the day of judgment.
But some people will encounter the power of God’s Word and Spirit before the day of judgment. When God uses his Word to work faith in their hearts, they will see themselves clearly, as sinners in need of God’s salvation.
With the phrase falling on his face,
Paul describes (perhaps figuratively rather than literally) the convert’s humble submission to the true God. The confession, God is really among you,
is taken from another of Isaiah’s prophecies: “The wealth of Egypt and the merchandise of Cush, and the Sabeans, men of stature, shall come over to you and be yours; they shall follow you; they shall come over in chains and bow down to you. They will plead with you, saying: ‘Surely God is in you, and there is no other, no god besides him’” (Isaiah 45:14).
Paul’s encouragement to the Corinthians should still serve as an encouragement for the church today. It is through the clear preaching of God’s Word (and not through spectacular phenomena) that the Holy Spirit brings sinners to repentance. Wherever the gospel is faithfully preached, the church can be encouraged to know that God is among them.
25 the secrets of his heart are disclosed, and so, falling on his face, he will worship God and declare that God is really among you.