13till we all come to the unity of the faith and of the knowledge of the Son of God, to a perfect man, to the measure of the stature of the fullness of Christ; 14that we should no longer be children, tossed to and fro and carried about with every wind of doctrine, by the trickery of men, in the cunning craftiness of deceitful plotting, 15but, speaking the truth in love, may grow up in all things into Him who is the head—Christ— Ephesians 4:13-15(NKJV)
Spiritual maturity is not long time spent in Salvation. It is not having a lot of head knowledge of the Bible. One is not spiritually mature because they are a pastor, prophet, or apostle. Positions or titles like deacon, elder, reverend, or bishop do not prove one is spiritually mature. Operating in spiritual gifts isn’t an indicator of spiritual maturity. The Corinthian church operated in spiritual gifts but they were babes and very carnal.
The perfect knowledge of the fullness of Christ and acting in that knowledge is what spiritual maturity is all about.
Being and living like Christ is spiritual maturity.
Living and walking the truth in love is spiritual maturity.