Togethter in Christ #19

Paul is giving us the reasons and ways to walk worthy of this wonderful inheritance we have in Christ. Having spent chapter 4 on emphasizing loving unity within the body, the household, he tells us what to avoid: 

3 But sexual immorality and all impurity or covetousness must not even be named among you, as is proper among saints. 4 Let there be no filthiness nor foolish talk nor crude joking, which are out of place, but instead let there be thanksgiving. 5 For you may be sure of this, that everyone who is sexually immoral or impure, or who is covetous (that is, an idolater), has no inheritance in the kingdom of Christ and God. 6 Let no one deceive you with empty words, for because of these things the wrath of God comes upon the sons of disobedience. 7 Therefore do not become partners with them;

Closely tied with worshiping an serving idols in the Gentile world was immorality in all its forms. At the top of the list is sexual immorality. As Paul points out here, as well as elsewhere, this involves our thinking, our speech, and actual adultery with our bodies. It includes things like pornography, lust, joking, innuendo, and any physical relationship outside of husband and wife. Paul also mentions impurity, a more general term which may include all sorts of ways our words and actions inject evil into others' lives. And always nearby to immorality is covetousness - always wanting more stuff, more experiences, more of whatever will make me feel good at the expense of others.  These are all inconsistent with Christlikeness. Paul really comes down hard on them; he is not soft on sin in the body. So whereas we are to demonstrate the love of God in the body, there are to be no lusts of the world inside it.