What constitutes spiritual maturity?
Doing more? Not at all. Believing is the greater challenge of man, whereas obedience to the law only precipitates a fall from grace:
"Stand fast therefore in the liberty wherewith Christ hath made us free, and be not entangled again with the yoke of bondage.
"Behold, I Paul say unto you, that if ye be circumcised, Christ shall profit you nothing.
"For I testify again to every man that is circumcised, that he is a debtor to do the whole law.
"Christ is become of no effect unto you, whosoever of you are justified by the law; ye are fallen from grace.
"For we through the Spirit wait for the hope of righteousness by faith.
"For in Jesus Christ neither circumcision availeth any thing, nor uncircumcision; but faith which worketh by love." (Galatians 5: 1-6)
Notice how Paul points out that in order to live under the law, an adherent is a "debtor" to fulfill the whole canon of Mosaic law. There is no "trying", either a man succeeds to keep the law, or he fails entirely, even if he stumbles in one (cf James 2:10) Imagine trying to do anything, only to find that from the outset you are behind, already in debt!
Grace is the infinite supply (cf 2 Corinthians 9:8) which enables and emboldens the believer to obey without even trying, for "faith which worketh by love" speaks of God's love in us (cf 1 John 4:19) and the faith we live by is straight from the throne of God Himself (cf Galatians 2:20)
So, what constitutes spiritual maturity, if not doing more? What does a mature Christian believe?
John gives a clue in his first general epistle:
"I write unto you, fathers, because ye have known him that is from the beginning." (1 John 2:13)
John repeats this characterization of the fathers in the next verse.
What does it mean, then, to know "Him that is from the beginning"?
First of all, the "Him" whom John is writing of here is Jesus Christ
"In the beginning was the Word, and the Word was with God, and the Word was God."
(John 1:1)
First of all, the knowledge of the Fathers in the First Epistle is in direct contrast to the "little children" whom John writes to, who "have known the Father."
Knowing the love of the Father is elemental for a Christian, which is made explicitly known to us through the death of His Son for our sins:
"In this was manifested the love of God toward us, because that God sent his only begotten Son into the world, that we might live through him." (1 John 4:9)
Spiritual Fathers, beyond those who are nourished not just in the knowledge of the complete forgiveness of sins (cf 1 John 2:12) and their triumph over the wiles of the enemy through their knowledge of God's Word (cf 1 John 2: 13-14), have received a greater revelation of Jesus Christ — they know Him who has been from the beginning.
What specifically do they know? Let's refer back to the first chapter of John's Gospel:
"All things were made by him; and without him was not any thing made that was made." (John 1:3)
Spiritually mature believers recognize by faith that Jesus is not just the Son of God who died for our sin, but that He is God, preeminent and infinitely power in his standing. Furthermore, they recognize that all things were made by Him, and that through His restored dominion in our lives, we can enjoy the same power in this world:
"Whether Paul, or Apollos, or Cephas, or the world, or life, or death, or things present, or things to come; all are yours;
"And ye are Christ's; and Christ is God's." (1 Corinthians 3:22-23)
John later writes:
"Ye are of God, little children, and have overcome them: because greater is he that is in you, than he that is in the world." (1 John 4:4)
Followed by:
"Herein is our love made perfect, that we may have boldness in the day of judgment: because as he is, so are we in this world." (1 John 4:17)
Jesus is not just the propitiation for our sins, He is the uncompromising power of God, and He is made manifest in our lives!
With Jesus Christ seated at the right hand of the Father, there we are also. What grand legacy do we enjoy as believers restored in oneness with Christ?:
"And ye are complete in him, which is the head of all principality and power:
"In whom also ye are circumcised with the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of Christ:
"Buried with him in baptism, wherein also ye are risen with him through the faith of the operation of God, who hath raised him from the dead.
"And you, being dead in your sins and the uncircumcision of your flesh, hath he quickened together with him, having forgiven you all trespasses;
"Blotting out the handwriting of ordinances that was against us, which was contrary to us, and took it out of the way, nailing it to his cross;
"And having spoiled principalities and powers, he made a shew of them openly, triumphing over them in it." ( Colossians 2: 10-15)
From the forever cleansing of all our sins (past, present, future), we are complete in Him, the head of all creation (so, we lack not one thing! Ponder that whenever any lack faces you in your daily life). The law ("the writing of ordinances") has no more power to condemn us, as every believer is now made the righteousness of God in Christ (cf 2 Corinthians 5:21), and every spiritual enemy has been forever "spoiled", or disarmed. Now that's victory!
In the next verse of John's gospel, we gather another clue to the greater revelation that spiritual fathers have of Jesus Christ:
"In him was life; and the life was the light of men."
Jesus Christ is the Way, the Truth, and the Life (cf John 14:6). He is everything for the believer, from the Shepherd (cf), to the Lamb of God, to the Bread of Life, to the Water of Life. He is our sustenance, He is our breath, our very heartbeat. The same Creator of all is made one with every one of us and informs, infuses, and instills power and wonder in our lives.
When a believer receives this growing revelation of the totality of Christ Jesus in our lives, he will know Him "that is from the beginning."
From the beginning to end, Jesus is the Author and Finisher of our faith (cf Hebrews 12:2). He brings us into new life, He leads us through this life, He provides for us throughout this life, He is our eternal life, one and inseparable, now and forever, Amen and Amen!
When you reflect on this grand wonder, beyond human calculation, you can only sense from within the grander and greatness of your status as a believer, a spiritual father in deed and truth!