“But let each one test his own work, and then his reason to boast will be in himself alone and not in his neighbor” (v4). Paul warns us to keep our eyes on Christ and our own behavior, rather than criticizing or comparing ourselves to others. We should show mercy and help to those who need it (v1-2), but in doing so, we shouldn’t “deceive ourselves” that we are superior; we also have weaknesses (v3). In the end, we are responsible for our own choices and opportunities (v8-10).
Holiness doesn’t come from “a good showing” or outward conformity (v12-14); it flows out of the transformation of our hearts, the “new creation” made possible by the cross of Jesus.