1 Corinthians 5:13

But them that are without God judgeth. Therefore put away from among yourselves that wicked person (KJV)

Then: In closing this topic, Paul reminds Corinthians that the unchurched are judged in secular systems. Then he ends by going back to the Old Testament directions for stoning convicted suspects found in Deuteronomy 17:7 (Baker p. 84). The Israelites had to put away evil from among themslves. For Paul, the reference is a restatement of purpose, and for New Testament Christians, the sentence of expulsion is not absolute because it leaves hope for a change of heart and renewed fellowship.

Now: For Christians, separation from the Lord is death. The earthly actions of the church mimic spiritual spiritual reality. When Jesus speaks to his disciples about dealing with unrepentant brothers, he explains that what they bind on earth will also be bound in heaven. No one should take disciplinary action of a church lightly. Eternal consequences are at the door. At the same time, no one should forget the merciful open arms of Christ extended towards his children inviting them to repent and come back to his love.

Extra source: Cornerstone Biblical Commentary 1 Corinthians (William Baker), 2 Corinthians (Ralph Martin & Carl Toney), ed. by Philip Comfort. Carol Stream: Tyndale House Publishers, c2006.