Gospel Fuel for Christians

I love (and agree) with this quote from Tullian Tchividjian:

... I once assumed (along with the vast majority of professing Christians) that the gospel was simply what non-Christians must believe in order to be saved, while afterward we advance to deeper theological waters. But I’ve come to realize that “the gospel isn’t the first step in a stairway of truths, but more like the hub in a wheel of truth.” As Tim Keller explains it, the gospel isn’t simply the ABCs of Christianity, but the A-through-Z. The gospel doesn’t just ignite the Christian life; it’s the fuel that keeps Christians going every day. Once God rescues sinners, his plan isn’t to steer them beyond the gospel, but to move them more deeply into it. After all, the only antidote to sin is the gospel—and since Christians remain sinners even after they’re converted, the gospel must be the medicine a Christian takes every day. Since we never leave off sinning, we can never leave the gospel.