21 And you, who once were alienated and hostile in mind, doing evil deeds, 22 he has now reconciled in his body of flesh by his death, in order to present you holy and blameless and above reproach before him, 23 if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister.
Colossians 1:21-23 

This annotation is a serious call for perseverance in the gospel. If we don’t continue in the gospel, the purpose of the atoning work of Christ on the cross will be in vain.  However, we know that God is faithful to complete that which he began in us (Phil. 1:6) as He works in us both to desire and to do according to His good pleasure (Phil. 2:12-13).  So every believer will perseverance, and they will do so by “continuing in the faith” – that is, not shifting from the hope of the gospel. Simply put, the gospel is the means of perseverance in the Christian life.

God has not left us to become holy, blameless, and above reproach by ourselves. God takes the responsibility of doing that. He’s going to present us this way. But He’s doing to do it in a way that maximizes the magnitude of His Son’s life, death, and resurrection.  God has so orchestrated the Christian life that every contributing factor to our sanctification and ultimately glorification is a manifestation of “the hope of the gospel.” The more we continue in it, the more “stable and steadfast” we become as God’s purpose of conforming us into the image of His Son is realized.

Don’t let the “if” in verse 23 pass you by. It is weighty. It demolishes the idea of the Christian life where the gospel is conspicuously absent. God is working to present trophies of His grace, and each step of perseverance in the gospel is a refining, polishing part of that process. The reconciling work of Jesus in verse 22 secures the conditional work of gospel perseverance in verse 23. The centrality of the gospel is absolutely necessary because of the purpose of the gospel, namely God’s presentation of believers who are “holy and blameless and above reproach before him.”

So hope in the gospel! It cannot be exhausted! The surety of your steps and sustaining power of your faith is fueled by remembering, rediscovering, and rejoicing in all that God is for you in His Son Jesus. This is what it means to be gospel-centered, and this is how God magnifies the finished work of Christ as it is daily applied for the final presentation of all His people under heaven for all time!