Clearly stated

Real change does not and cannot come independently of the gospel, which is the good news that even though we’re more defective and lost than we ever imagined, we can be more accepted and loved than we ever dared hope, because Jesus Christ lived, died, and rose again for sinners like you and me.

Tchividjian, Tullian (2010-04-23). Surprised by Grace: God's Relentless Pursuit of Rebels (pp. 16-17). Crossway. Kindle Edition.

The answer isn’t to try harder in the Christian life but to comprehend more fully and clearly Christ’s incredible work on the cross, and then to live in a more vital awareness of that grace day by day.

Tchividjian, Tullian (2010-04-23). Surprised by Grace: God's Relentless Pursuit of Rebels (p. 17). Crossway. Kindle Edition.

Yeah, I can't say it much better or clearer than the second quote, so I won't even try.