The letter starts like a typical ancient Greco-Roman letter. Paul introduces himself as "an apostle of Christ Jesus" called by God, establishing his authority to shepherd the Corinthian church. Sosthenes is likely Paul's coworker present when he writes this letter.

In the New Testament, "church" usually refers to local gatherings of believers, not to a physical building. Believers meet with the church to worship, preach the Bible, perform baptisms, celebrate the Lord's Supper, and practice church discipline. Paul describes the Corinthian church as "sanctified in Christ Jesus" and "called to be saints." They are already holy, but God calls them to live holy lives. Paul blesses the recipients and specifies God as the source of grace and peace.

Paul thanks God for the Corinthians because God gave them sustaining grace in Christ Jesus. God confirmed Paul's testimony about Christ and the gospel to the Corinthians. As a result, the Corinthians will persevere in faith while waiting for Jesus' return. Jesus will sustain them until the very end, ensuring their guiltlessness.

Paul shifts from affirming the Corinthians to gently confronting their divisions. He appeals for unity, not division over teachers. While agreement doesn't imply total conformity, the church must be united on the gospel and its implications. Chloe's people reported quarrels over following certain teachers. Some claim allegiance to specific teachers, while others sanctimoniously claim to follow Christ. Paul asks, "Is Christ divided?" Contrasting baptism and preaching, he emphasizes his primary calling. He does not diminish baptism.

Unbelievers may find a crucified Messiah silly and absurd, but believers treasure the good news that Jesus, mocked as king, reigned from a cross. Sinful humans may think they are smarter than God and demand explanations, but God demolishes such folly. Through the preaching of Paul and others, God made worldly wisdom appear foolish by proclaiming a crucified Messiah. This pleased God, who wisely planned to save believers despite the "wise" world considering it folly.

Paul highlights two types of worldly wisdom's idolatry: (1) Jews expected a mighty deliverance from bondage by the Messiah and rejected a crucified Messiah as repulsive, thinking that crucifixion symbolized God's curse on the victim. (2) Greeks sought what they perceived as rational and beautiful, and they considered crucifixion as a criminal's defeat, leading them to reject a crucified Messiah as absurd and ugly. Crucifixion conveys shame, weakness, failure, loss, and scandalous evil, while Messiah conveys grandeur, strength, success, victory, and the highest honor. However, the crucified Messiah embodies God's power and wisdom. God's "foolishness" surpasses any wisdom the world offers, just as His "weakness" far exceeds human strength.

God wisely chose unexpected people: uneducated, noninfluential, and disdained. They shame and invalidate the elite. Throughout history, God's people boast in Jesus, our righteousness, sanctification, and redemption. Believers are in Christ Jesus, boasting only in the Lord.