There seems to have been a few question and some confusion over this one. I offer a few thoughts.
1. Having sex with someone and therefore becoming 'one flesh' does not mean that you have entered into marriage with them. What Paul is arguing for in 1 Corinthians 6 is the inappropriateness of engaging in sex which is meant for marriage, when you're not married. He's not arguing that it is marriage, or that you need to get married if you have had sex with someone....wow, I can sense some more questions coming back at me on that one...
2. Some of us feel the pain and grief of the mistakes of our past and need to be embraced by the full and transforming power of Christ's forgiveness. Does it mean that you can call yourself a virgin again? No it doesn't, but in God's eyes if you have received Christ as Lord you cannot be any cleaner or purer or distanced from those events in your past. Though some regret and shame may remain, it becomes all the more a testimony to God's grace and kindness to you.
3. If you have been the victim of some abuse and have been sexually violated by someone else there is great pain and hurt which only Christ can ultimately deal with. He heals the broken hearted and comforts the abused. The gospel shows you how powerful and significant is the acceptance and plans of Christ who not only removes our own personal sin, but also deals with sin done to us. The gospel will protect us from feeling worthless and ashamed and will help us not to feed our bitterness and hatred of the perpetrator, and even of God himself.
I know these are very hard areas for some of us. But I know that God is the master of dealing with our sin ravaged world and making all things new. Please trust his Word and perhaps aim to talk to someone you can trust so as to further experience the newness of life he has called you to.
