1It is actually reported that there is sexual immorality among you, and such sexual immorality as is not even named among the Gentiles, that one has his father’s wife. 2You are arrogant, and didn’t mourn instead, that he who had done this deed might be removed from among you. 3For I most certainly, as being absent in body but present in spirit, have already, as though I were present, judged him who has done this thing. 4In the name of our Lord Jesus Christ, when you are gathered together with my spirit with the power of our Lord Jesus Christ, 5you are to deliver such a one to Satan for the destruction of the flesh, that the spirit may be saved in the day of the Lord Jesus.
6Your boasting is not good. Don’t you know that a little yeast leavens the whole lump? 7Purge out the old yeast, that you may be a new lump, even as you are unleavened. For indeed Christ, our Passover, has been sacrificed in our place. 8Therefore let’s keep the feast, not with old yeast, neither with the yeast of malice and wickedness, but with the unleavened bread of sincerity and truth.
9I wrote to you in my letter to have no company with sexual sinners; 10yet not at all meaning with the sexual sinners of this world, or with the covetous and extortionists, or with idolaters, for then you would have to leave the world. 11But as it is, I wrote to you not to associate with anyone who is called a brother who is a sexual sinner, or covetous, or an idolater, or a slanderer, or a drunkard, or an extortionist. Don’t even eat with such a person. 12For what do I have to do with also judging those who are outside? Don’t you judge those who are within? 13But those who are outside, God judges. “Put away the wicked man from among yourselves.”
(Gk. πορνεια, porneia). Strong's: 4202 (19: 9; John 8: 41; 1 Cor 5: 1; 7: 2; Eph 5: 3; 1 Thess 4: 3)
Fornication refers to sexual intercourse outside a proper marriage relationship. The nature of the sexual relationship is to bond together permanently a man and woman, making them one flesh. This is God’s design, although He gives a concession in Deut 24: 1- 4 allowing divorce, to which this passage refers. The nature of the sexual bond argues for the foolishness of promiscuity, doing damage to the marital bond or to one’s ability to successfully make that bond in the future. Though one may avoid the physical diseases associated with promiscuity, it is not possible to avoid the damage fornication wrecks on the soul.