The opposite of mortifying sin (putting it to death) includes excusing sin, tolerating sin, or merely wounding sin by attempting to manage it.  Mortification is Holy Spirit-enabled conviction followed by repentance of sin, faith in God, worship of God, and perseverance in holiness so that sin remains dead and joy remains alive.

Mark Driscoll, Doctrine, 161

Sin hurts other people and grieves God, but it also corrodes us.  Sin is a form of self-abuse.

Cornelius Plantinga Jr., Not The Way It’s Supposed to Be, 124

When we sin as image bearers of God, we are saying to the whole creation, to all of nature under our dominion, to the birds of the air and the beasts of the field:  “This is how God is.  This is how your Creator behaves.  Look in his mirror; look at us, and you will see the character of the Almighty.”  We say to the world, “God is covetous; God is ruthless; God is bitter; God is a murderer, a thief, a slanderer, an adulterer.  God is all of these things that we are doing.”

R.C. Sproul, The Holiness of God, 116.