What is spiritual maturity? What is it to go on in the Lord? I fear we have got mixed ideas about this. Many think that spiritual maturity is a more comprehensive knowledge of Christian doctrine, a larger grasp of scriptural truth, a wider expanse of the knowledge of the things of God; and many such features are recorded as marks of growth, development, spiritual maturity. Beloved, it is nothing of the kind. The hallmark of true spiritual development and maturity is this: that we have grown so much less and the Lord Jesus has grown so much more. The mature soul is one who is small in his or her own eyes, but in whose eyes the Lord Jesus is great. That is growth. We may know a very great deal, have a wonderful grasp of doctrine, of teaching, of truth, even of the Scriptures, and yet be spiritually very small, very immature, very childish. (There is all the difference between being childish and childlike.) Real spiritual growth is just this: I decrease, He increases. It is the Lord Jesus becoming more. You can test spiritual growth by that.
In the book of the Acts, they did not first of all preach Jesus as Savior. They preached Him as Lord. You see, that carried with it of necessity the Savior-hood. He must be the Christ, He must be the Savior, He must be the Son of God. All THAT is involved if He is Lord now; and if they accepted and acknowledged Him as Lord, well, that included His Savior-hood, but the Savior-hood was something subsidiary to the Lordship.
After all, the Savior-hood of Christ is but a recovering thing in relation to His Lordship. The Lordship was the eternal intention of God concerning Him. The Savior-hood is in order to get back to the Lordship, to lead on to the recovery of the Lordship. He can never be actually Lord until He has saved the inheritance of which He is the eternally designated Lord; but when He is Lord, it means that He is Savior; He HAS redeemed. The Lordship is more than the Savior-hood. And so, when you come on to God’s SUPREME ground “hath made him a Prince and a Savior” then the way is open for God to take you right on, beyond conversion, beyond the infant stage of just being born again; on to ‘growing up into Him in all things’, on to the fullness of Christ. So they put the full testimony there, where all the rest was included, and thus there was a wide open way for all God’s intention. Wherever you look in the Scriptures, you find that it is Lordship which is the secret of fullness.