I feel he knows what would be best for himself. After all it's his mind that he is opening to the world. Asking God to guard our minds is very important but we are told not to put God to the test. By indulging in things that bring the world more and more into our minds and bodies, we are definitely putting God to the test.
It may not be an outright, conscience sin, but it sure isn't healthy or safe. Much like we have learned here at curezone about what is healthy living and what is not. And also much like this scripture about how allowing a prostitute to invade our bodies, also invades our oneness with God.
The Body Is the Lord’s
12All things are lawful for me, but not all things are profitable. All things are lawful for me, but I will not be mastered by anything.13Food is for the stomach and the stomach is for food, but God will do away with both of them. Yet the body is not for immorality, but for the Lord, and the Lord is for the body.14Now God has not only raised the Lord, but will also raise us up through His power.15Do you not know that your bodies are members of Christ? Shall I then take away the members of Christ and make them members of a prostitute? May it never be!16Or do you not know that the one who joins himself to a prostitute is one body with her? For He says, “THE TWO SHALL BECOME ONE FLESH.”17But the one who joins himself to the Lord is one spirit with Him.18Flee immorality. Every other sin that a man commits is outside the body, but the immoral man sins against his own body.19Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own?20For you have been bought with a price: therefore glorify God in your body.
Matthew Henry's Concise Commentary
6:12-20 Some among the Corinthians seem to have been ready to say, All things are lawful for me. This dangerous conceit St. Paul opposes. There is a liberty wherewith Christ has made us free, in which we must stand fast. But surely a Christian would never put himself into the power of any bodily appetite. The body is for the Lord; is to be an instrument of righteousness to holiness, therefore is never to be made an instrument of sin. It is an honour to the body, that Jesus Christ was raised from the dead; and it will be an honour to our bodies, that they will be raised. The hope of a resurrection to glory, should keep Christians from dishonouring their bodies by fleshly lusts. And if the soul be united to Christ by faith, the whole man is become a member of his spiritual body. Other vices may be conquered in fight; that here cautioned against, only by flight. And vast multitudes are cut off by this vice in its various forms and consequences. Its effects fall not only directly upon the body, but often upon the mind. Our bodies have been redeemed from deserved condemnation and hopeless slavery by the atoning sacrifice of Christ. We are to be clean, as vessels fitted for our Master's use. Being united to Christ as one spirit, and bought with a price of unspeakable value, the believer should consider himself as wholly the Lord's, by the strongest ties. May we make it our business, to the latest day and hour of our lives, to glorify God with our bodies, and with our spirits which are his.