Romans 6:21

What fruit, then ... - What reward, or what advantage. This is an argument drawn from the experience of Christians respecting the indulgence of sinful passions. The question discussed throughout this chapter is, whether the gospel plan of justification by faith leads to indulgence in sin? The argument here is drawn from the past experience which Christians have had in the ways of transgression. They have tried it; they know its effects; they have tasted its bitterness; they have reaped its fruits. It is implied here that having once experienced these effects, and knowing the tendency of sin, they will not indulge in it now; compare Romans 7:5.

Whereof ye are now ashamed - Having seen their nature and tendency, you are now ashamed of them; compare Romans 1; Ephesians 5:12, “For it is a shame to speak of those things which are done of them in secret,” 2 Corinthians 4:2; Jude 1:13; Philippians 3:19.

For the end - The tendency; the result. Those things lead to death.

Is death - Note, Romans 6:22.