The form of 'grace' we have today is like an asthma patient who's given an inhaler to relieve their symptoms. The patient is grateful for the new freedom in their lungs, but the inhaler never cures the asthma: it only treats it temporarily.
I've recently come across an increasing number of very devoted followers of Jesus who believe in grace primarily as an act of pardon: "You're off the hook, now." And, they may also believe in grace as the action of God in them to produce goodness and Christlike character. But this form of grace will always be stunted, cut short by their view of the heart.
If the believer's heart hasn't been thoroughly renovated -- no, replaced -- by the very heart of Jesus, then this stunted form of grace is actually a cruelty. The resulting effect of stunted grace goes like this: "You're off the hook now because of God's grace; and he is indeed working in you to make you more Christ-like; but, because your heart is still sinful (desperately wicked) and prone to wander, you're probably not going to do very well at this holiness thing. Why? Because your heart is still bent on self-will and preoccupied with getting life on its own terms. Try harder next time (by God's grace) to not let your diseased and corrupt heart get in the way of this new holiness you're after.
Doesn't this seem a bit cruel to you? The problem with stunted grace is that it doesn't address the root problem: the heart needs an overall, and the rescuing work of Jesus has to go beyond pardon. It must go straight for the heart. And .... thankfully, it did.
Is it possible to "love God with all your heart" if your heart remains dark and prone to wander? Would God ask such a thing of us, knowing it sets us up for failure? "You're required to love me with your truest self, but you won't be able to. " It's similar to offering a man on death row a pardon, releasing him from his debt, but then asking him to function as a healed man in society.
How cruel it would be to expect a man with a shattered leg to climb Everest, pressuring him to be more committed to the task, admonishing him to have more faith, all the while knowing he can only do it if his limb is first restored.
First, you heal the man of the disease that sentenced him in the first place, then you ask him to live the life of Jesus -- out of that restoration.
To be sure, there will continue to be competing desires in a person, for the person's old heart/nature is still present, yet the believer is clearly a new creation with his identity firmly secured by his restoration. His new heart is now the center of his identity. "God became man to turn creatures into sons; not simply to produce better men of the old kind but to produce a new kind of man. " -- C. S. Lewis
What does it mean that we are 'new creations in Christ' if it does not include the rescue of our hearts? If we first stray with our hearts, we can also (following our rescue) return with our hearts. The heart is at the center of it all.
"Grace" is the gift of a restored and noble heart.