Denominations are formed when we choose to divide the one body of Christ and establish a false unity around anything other than our Head, the Lord Jesus Christ and our common faith in His gospel.

This false unity can even be uniting around a particular doctrine/truth rather than Christ and Him crucified.

Jesus Christ died for our sins, He was buried, and He rose again the third day for our justification.

If we believe the gospel of Christ, then we are brethren in the one body of Christ, His church.

Whether mature or immature, that is a different matter.

The rest of our Christian lives is
- Abba Father's chastening in love,
- sanctification,
- repenting (changing our minds),
- renewing our minds, 
- departing from iniquity, 
- faith working itself out in love,
- being conformed to the image of Christ (which includes the mind of Christ)
- growing in the unity of the faith and knowledge of the Son of God (which is to know Him),

...all for God's glory.

These are all connected and intertwined.

Ephesians 4:13-16
till 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; that 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, but, speaking the truth in love, may grow up in all things into Him who is the head—Christ— from whom the whole body, joined and knit together by what every joint supplies, according to the effective working by which every part does its share, causes growth of the body for the edifying of itself in love.

Philippians 3:7-11
But what things were gain to me, these I have counted loss for Christ. 

Yet indeed I also count all things loss 

👉 for the excellence of the knowledge of Christ Jesus my Lord, 

for whom I have suffered the loss of all things, and count them as rubbish, that I may gain Christ and be found in Him, not having my own righteousness, which is from the law, but that which is through faith in Christ, the righteousness which is from God by faith; 

👉 that I may know Him 

👉 and the power of His resurrection,

👉 and the fellowship of His sufferings,

being conformed to His death, if, by any means, I may attain to the resurrection from the dead.