7:1 Cleansing is a twofold action: turning away from sin, and turning toward God. The Corinthians were to have nothing to do with paganism. They were to make a clean break with their past and give themselves to God alone. The phrase “perfecting holiness” connotes becoming mature or complete. Thus, Paul wasn’t suggesting that the Corinthians could become sinless in this life. Instead, he was prodding them to work at maturing in their faith. God had provided them with all the resources they needed, and Christ’s Spirit would empower them to become Christlike (Romans 8:2).
7:2 Paul insisted that the Corinthians should open their hearts for him. He knew how much those in the church need one another. If fellowship was necessary in Paul’s day, it is all the more crucial today, when time is more valuable than money. Each day holds barely enough time to care for personal and family needs, let alone to meet the needs of others. Yet the activities that occupy our time are not as important as the community described in these verses. Paul’s intention is not “coffee and donuts between church” fellowship. Believers need accountability that comes from lives intertwined by the cords of commitment and love. If you are not in a small group Bible study, take the first steps. Offer hospitality to fellow believers; when others extend the hand of fellowship to you, grasp it enthusiastically.
7:8ff “A letter” refers to the third letter (now lost) that Paul had written to the Corinthians. Apparently it had caused the people to begin to change. For an explanation of the chronology of Paul’s letters to Corinth, see the first note on 1:1.
7:10 Sorrow for our sins can result in changed behavior. Many people are sorry only for the effects of their sins or for being caught (sorrow “of the world”). Compare Peter’s remorse and repentance with Judas’s bitterness and suicide. Both denied Christ. One repented and was restored to faith and service; the other took his own life.
7:11 Paul affirmed the Corinthians for their right response to the correction he had given them. It’s difficult to accept criticism, correction, or rebuke with poise and grace. It is much more natural to be defensive and then counterattack. We can accept criticism with self-pity, thinking we don’t really deserve it. We can be angry and resentful. But a mature Christian should graciously accept constructive criticism, sincerely evaluate it, and grow from it.