For followers of Jesus, maturity has to do with conformity to Christ. Ephesians 4:13 says:
The purpose of this is that we should all reach unity in our belief and loyalty, and in knowing God’s son. Then we shall reach the stature of the mature [telos] Man measured by the standards of the Messiah’s fullness.
The Greek word for 'mature' is telos. Telos can be translated as 'end,' or 'purpose.' Or 'goal.' Like a telos-scope; namely, an ocular assistant that allows one to see to the end of things.
The NIV’s “attaining to the whole measure of the fullness of Christ” points to Paul’s concern about maturity in the here and now—a faith that reaches an adult wholeness. What is maturity? You measure it by who Christ is. The Christian's goal on earth, to be fully realized in heaven, is formation into Christlikeness. (Gal. 4:19) As C. S. Lewis wrote,
“Every Christian is to become a little Christ. The whole purpose of becoming a Christian is simply nothing else.”
The apostle Paul's mission was to walk with Gentile Christians on the road to maturity. He writes, in Colossians 1:28-29,
28 He is the one we proclaim, admonishing and teaching everyone with all wisdom, so that we may present everyone fully mature in Christ. 29 To this end I strenuously contend with all the energy Christ so powerfully works in me.
How do you mature in Christ? Not by willpower. A strong will gives evidence of maturity. But willpower fails repeatedly as a method to produce maturity. Dallas Willard told us that "developing maturity based on willpower produces endless failures." (James Wilder, Renovated: God, Dallas Willard, and the Church That Transforms, pp. 32-33)
If not by willpower, then how? Coming in a future post.