"the gospel isn’t the first step in a stairway of truths, but more like the hub in a wheel of truth.” In other words, once God rescues sinners, his plan isn’t to steer them beyond the gospel, but to move them more deeply into it. All good theology, in fact, is an exposition of the gospel.In his letter to the Christians of Colossae, the apostle Paul portrays the gospel as the instrument of all continued growth and spiritual progress, even after a believer’s conversion.“All over the world,” he writes, “this gospel is bearing fruit and growing, just as it has been doing among you since the day you heard it and understood God’s grace in all its truth” (Col. 1:6). He means that the gospel is not only growing wider in the world but it’s also growing deeper in Christians.After meditating on Paul’s words, a friend told me that all our problems in life stem from our failure to apply the gospel. This means I can’t really move forward unless I learn more thoroughly the gospel’s content and how to apply it to all of life. Real change does not and cannot come independently of the gospel. God intends his Good News in Christ to mold and shape us at every point and in every way. It increasingly defines the way we think, feel, and live."
Tullian Tchividjian, The gospel everyday (read the full thing here)