Why weren't the Corinthians experiencing victory over their old lifestyle?
The Corinthians lacked victory because they had come out of abject paganism with no moral foundations or concept of the one true Creator God. Though they heard the gospel of saving grace and were set at liberty, they had not fully consummated God's grace for victory over their past lifestyle; they kept returning to it. Transformation would take time.
Les explains that the Corinthians were failing miserably despite the apostle's teaching and doctrines. The apostle wrote with anguish of heart and many tears, not to grieve them but to show his abundant love. They had come from abject paganism, ignorant of the one true Creator God, without the Old Testament that Israel had. They had recently heard the gospel of God's saving grace and were set at liberty, yet they had not consummated all of God's grace that gives victory over the past lifestyle. They were still dipping back into the old lifestyle, which grieved the apostle. Understanding their circumstances, he knew you cannot expect such people to suddenly live like Peter, James, and John; it would take time.