What is Gospel-centered?
I do not simply mean by ‘gospel-centered’ that ministry is to be doctrinally orthodox. Of course it must certainly be that. I am speaking more specifically. (1.) The gospel is “I am accepted through Christ, therefore I obey” while every other religion operates on the principle of “I obey, therefore I am accepted.” (2.) Martin Luther’s fundamental insight was that this latter principle, the principle of ‘religion’ is the deep default mode of the human heart. The heart continues to work in that way even after conversion to Christ. Though we recognize and embrace the principle of the gospel, our hearts will always be trying to return to the mode of self-salvation, which leads to much spiritual deadness, pride and strife, and ministry ineffectiveness. (3.) We must communicate the gospel clearly–not a click toward legalism and not a click toward license. Legalism/moralism is truth without grace (which is not real truth); relativism is grace without truth (which is not real grace). To the degree a ministry fails to do justice to both, it simply loses life-changing power.
Tim Keller, Advancing the Gospel into the 21st Century