This book is called I Corinthians because it is the first of two letters addressed to the church of God at Corinth (I Corinthians 1:1).
In I Corinthians 1:1 we learn that Paul, "an apostle of Christ Jesus," was the writer. The lesson sheet on Romans reviews his life.
According to best chronology, and from statements found in Acts 19, it has been generally concluded that Paul wrote the letter from Ephesus in the spring of A.D. 57.
At the time Paul visited it, Corinth was the chief city of Greece, with around 400,000 inhabitants. It had two harbors and enjoyed great commercial activity. Its metropolitan population included Jews, Greeks, Italians, Romans, Syrians, Egyptians, sailors, traders and slaves. Its wealth was as proverbial as the vice and profligacy of its inhabitants. Religion and philosophy had been prostituted, and intellectuality was placed above moral life. Pagan vices were prevalent and idolatry was rampant. Such a premium was placed on prostitution that the expression "a Corinthian woman" became synonymous with a harlot.
Paul established the Corinthian church on his second missionary tour (Acts 18:1-18). About three years prior to this letter he entered Corinth alone. Later he was joined by Silas and Timothy from Macedonia. For eighteen months Paul worked night and day. While there he made his home with Aquila and Priscilla, who were tent-makers. As a result of his labors, "many of the Corinthians hearing believed, and were baptized" (Acts 18:8). After leaving Corinth, Paul came to Ephesus and later went back to Jerusalem and Antioch (Acts 18:18-22). In the meantime, Apollos worked some with the church at Corinth (Acts 18:24-28; 19:1).
On his third tour Paul returned to Ephesus where he spent three years (Acts 19; 20:31). While he was there, some members of the Corinthian church, Stephanas, Fortunatus, Achaicus, and members of the house of Chloe (1:1; 16:17), visited him and brought unfavorable news concerning moral and spiritual conditions in Corinth. The city was one of the most wicked of ancient times, and many shameful practices and departures had developed in the church. News regarding such an unfavorable situation served as the occasion for this letter.
The purpose of the letter was to correct the immoral practices and doctrinal errors which had developed in the congregation. The Corinthian correspondence is an excellent textbook on local church life.