foolish (v.4) = lack of forethought and wisdom — foolish and sinful
coarse jesting (v.4) = lit. “easily turned” = polished and witty speech as the instrument of sin, ribaldry
you know (v.5) = you know for sure, you are aware, self-evident knowledge, absolute conviction
fornicator (v.5) = one who indulges in unlawful sexual conduct (the word can sometimes refer to a male prostitute)
unclean (v.5) = unclean in thought or life
covetous (v.5) = one eager to have more, especially of what belongs to others
This passage and its counterpart in Galatians poses a perplexing problem for many. Some have concluded from Paul’s statement that those who commit such sins will lose their salvation. But it must be remembered here that there is an underlying principle to consider. Under the law, the sacrificial system was designed to only cover sins of ignorance. No provision was made for presumptuous sins, for God was unwilling to even entertain the thought that His people would ever sin against Him willingly (Numbers 15:27-31)
Paul follows the same line of thought, insofar as those who walk in love and understand the sufferings of Christ would never be guilty of such sins. “for this ye know, those who live in sin are dead while they liveth,” and therefore shall never inherit the kingdom of Christ. However,we are the redeemed who have been forgiven in Christ — recipients of the heavenly inheritance (2 Timothy 4:18). But what if a believer should fall from grace and commit one of these sins? We shall answer this query with two questions: Does not the blood of Jesus Christ cleanse from all sin? And, “Who shall separate us from the love of Christ?” — Sadler, pages 225-226
I agree with Sadler that the saved can’t lose their salvation, even when they sin. Paul had already established earlier in this book that he was writing to the saved. You can’t take one verse and use it to overturn a doctrine well established elsewhere. Take a look at the Corinthian Christians and their sins. Paul chastised them for their sin, but he never hinted that it lost them their salvation. Romans 7:15-25 is another example. So what is Paul saying here?
Here’s what I think. Ephesians is the book that shows us the full depth of what we have in Christ and what our response should be. These sins are ones that are committed, enjoyed and celebrated by the unsaved. They are the identifying character traits of the world. Why would a Christian want to be associated with them? Paul is saying, in essence, “These are the disgusting things done by those who have no part in God’s kingdom. These are the disgusting things done by those who aren’t in Christ. Do not let them be said of you who are saints.”
In the next verses, Paul calls the unsaved “the sons of disobedience” and urges the Christians to not be partakers with them. Then he goes on to remind them who they are in Christ. He’s not saying they won’t be in the kingdom of God. He’s saying that they shouldn’t do the things that are done by those who won’t be. He’s showing us just how disgusting sin is, and what God thinks of it. Knowing that, why would the saved want to get involved?