The Corinthian church started in Acts 18 as Paul visited that city. He first saw Crispus come to faith in the synagogue. Paul was there about one year and then continued on his journeys.
Paul finds out there were problems in Corinth, writes the letter (from Ephesus). Even though there were issues, he addresses them as "saints." We often think of saints as "super ,special holy people" and that is really who they are, but EVERY follower of Jesus is a saint!
Even though we are "saints," this is not something that we have done. If we've been rescued, it's because
He rescued us, not because we rescued ourselves. It's all about Jesus!
Paul reminds us "God chose the lowly things of this world and the despised things-and the things that are not-to nullify the things that are, so that no one may boast before him...just as it is written, 'Let him who boasts, boast in the Lord.' " (1 Cor 1:28-30 NIV)
Let's boast in Jesus, not in ourselves, because He is worth boasting in!