"The gospel is not only what we need most before coming to Christ—it is what we need most after coming to Christ! Romans 6 teaches us that at the cross Jesus freed us from the penalty and power of sin. That means we have not been defeated by sin! On the contrary, the gospel makes it possible for us to win against any sin we face.Think about that one sin which owns you—the one to which you easily and repeatedly submit. The gospel says not only do you not have to listen to its soul-shrinking temptations, but you can actually defeat it. You can tap it out in the cage of your life more often than it does you! That is the gospel’s glorious work when it comes to fighting our sin. It is the essential belief we must have in the forefront of our mind!"
Yancey Arrington, Fight Sin: Belief before behaviour (read the full thing here)