Why hadn't the Corinthians yet gained victory over their old lifestyle after hearing the gospel?
They had only recently heard the gospel after coming out of abject paganism, with no moral foundations and no knowledge of the one true Creator God or the Old Testament. Their transformation required time; they had not yet fully appropriated God's grace for victory and were still slipping back into old habits.
Les explains that the Corinthians had come out of abject paganism, with no moral foundations, no concept of the one true Creator God, and no Old Testament like Israel had. They had just recently heard the apostle preach the gospel of God's saving grace and had been set at liberty, yet they had not really consummated all of the grace of God that would give them victory over their past lifestyle. They were still dipping back into their old lifestyle, which grieved the apostle. But understanding their circumstances, he knew they could not all of a sudden live like Peter, James, and John did. It would take time.