A good conclusion reflects the introduction of the essay. It goes back over the main points that you have made. In this essay, then, your conclusion should go over the idea that God wants his people to enjoy sex in the proper context. It should give your main reasons for coming to this conclusion.
If your main support for this is the passage from I Corinthians, then you should refer back to the most salient verses. If you are bringing in the Tim Lane article that you were reading not too long ago, you should refer to it. In addition, if you are going to use any references from popular culture to show that people think Christians are anti-sex, you should refer to them as well.
Do not just restate your introduction word for word, but do have your conclusion echo your introduction. Remember, this is not the time to be bringing in new evidence. It is just the time to remind your readers of what you said in your essay as a whole.