Mature Christians have an awesome responsibility to help the less mature Christian grow up. Peter reminded the church leaders of Ephesus: “Be shepherds of God’s flock that is under your care, serving as overseers—not because you must, but because you are willing, as God wants you to be” (1 Peter 5:1).
But what happens when a Christian doesn’t want to grow? This is where the responsibility lies with that individual to want to grow, decide to grow, and make an effort to grow.
Spiritual growth doesn't just happen once you're saved, even if you attend church regularly. Our churches are filled with people who've attended all of their entire lives, yet they're still spiritual babies.
Spiritual growth must be intentional it is not automatic. The writer of Hebrews sadly noted, "... though by this time you ought to be teachers, you need someone to teach you the elementary truths of God's word all over again." (Heb. 5:12)
Millions of Christians have grown older without ever growing up spiritually. The truth is that spiritual growth requires a commitment to grow. Discipleship begins with a decision. It doesn't have to be a complex decision, but it does have to be sincere.
Philippians 2:12-13 says, "... continue to work out your salvation with fear and trembling, for it is God who works in you to will and to act according to his good purpose."
Notice that it says "work out" - not "work on" - your salvation. There is nothing you can add to what Christ did for your salvation. Paul is talking about spiritual growth in this passage to people who are already saved.
The important thing to note is that God has a part in our growth but so do we. We must make an intentional effort to grow.