1 Corinthians 5 - This chapter deals with the subject of sins which Christians can commit and how to deal with those who do. Reading this passage carefully you will see that the man in question is being talked about as a believer who is involved in gross immorality. The issue here is his apparent refusal to stop and the church's immobility in dealing with this. Paul basically says that this man should be "delivered...to Satan for the destruction of his flesh...that his spirit may be saved in the day of the Lord Jesus" verse 5. Paul does not speak of this man losing his salvation. But he rebukes the church for allowing this man to continue in his sin without confronting him. Later Paul speaks about not to keep close company with unbelievers, verse 9, but still maintain contact with them, verse 10. If a brother continues in sin then believers are to refrain from close contact with him/her.
1 Corinthians 6 - Paul criticized the Corinthian believers for resorting to outsiders to "judge" issues they were facing among themselves. This implies that mature Christians have the right to "judge" matters relating to other Christian's behavior and seek to bring about a healthy and appropriate resolution. Paul also reminds believers not to engage in sexual misconduct, especially in the practice of prostitution (which was rather rampant in that day). Paul clearly states that a believer's body is the "temple of the Holy Spirit" verse 19. Our bodies and lives were "bought with a price" verse 20. We owe it to God to keep our bodies and hearts pure before Him.
1 Corinthians 7 - Paul deals with the matter of marriage and whether it is right for a Christian to marry. That may sound unusual, but you must remember that during persecution it is easier for a single person to face it without having concern for their immediate loved ones. Pay attention to what he says in verses 29-40. Paul also speaks to believers who got saved while still married to someone who isn't, verses 12-16. The obvious desire here is to see the saved believer seek to win their unsaved mate to Christ.
1 Corinthians 8 - Though Paul elevates love above knowledge, verse 1, he does encourage having a good intellect regarding the prevalence of idolatry in his day. How does a Christian deal with idolatrous practices such as the offering of food to an idol before eating it. Some see the idol as nothing and don't concern themselves when they consume that food, verse 4-6. Other believers may take offense in doing so, verse 7. Paul encourages the "stronger" believer to respect the weaker believer's conscience and not doing anything that would offend.