Dennis Johnson writes:
“Spiritual maturity is derived only from living in union with Christ*, by faith and through the Spirit. Only in Christ and our union with him in his death and resurrection do believers find the motive and the powers to pursue growth in godliness and love.
Therefore, the same gospel that initially called us to faith is the means that perfects us in faith. As surely as Christ’s obedience, death, and resurrection constitute the all-sufficient, once-for-all ground for our justification by faith, so Christ’s righteous life, sacrificial death, and vindication in resurrection power are the fount from which flows our sanctification by faith as we grow in grace. The preaching that matures and edifies, no less than the preaching that evangelizes and converts, calls believers not “beyond” the gospel to “deeper mysteries” (as some were promising to the Colossian Christians [cf. Col. 2:16-23]) but more deeply into the gospel and its implications for our attitudes, affections, motivations, and actions.”
[Quoted from Dennis Johnson, Him We Proclaim: Preaching Christ From All the Scriptures (Phillipsburg, NJ: P&R Publishing, 2007), 68]
Dennis Johnson is Professor of Practical Theology at Westminster Seminary California.