13 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;
the unity of the faith
“Faith” here does not mean the act of belief but the content of what we believe, or doctrine. There is a definite article (“the”) before the word “faith” in this phrase, making the meaning the body of doctrine. The idea, then, is not faith as an act of trusting God. “Unity of faith” refers to unity in what we believe. True unity in the church comes from unity of belief. The Corinthian church needed this understanding after entering into divisions and schisms (1 Co 1:10).
The “unity of faith” is a coordinated system of doctrine and objective content of what we believe. Principles of life form from our understanding of Scripture and system of faith. Constant application of principles to experience over time will bring us to the stage of maturity or an edification construct.
“Unity of the faith” is not total doctrinal conformity among Christians, for the context here is unity around the person of Christ. There will never be agreement on every nuance of theology this side of heaven. Faith here refers to core doctrines about Christ. There is core truth around which all Christians must agree.
The primary unity of the church comes from unity in what we believe.
Without truth there is no true unity in the church. Those in a church that is well taught in the Word can come to maturity of understanding of their faith. To the level that they are not taught—to that level they will fragment. Any other unity rests on something less than unity of truth. Doctrinal integrity is at the heart of church unity.
Unity here is not total doctrinal conformity to doctrinal statements wherever they may exist. The idea in context is the core doctrines as they relate to Christ. Christian unity admits great diversity (1 Co 12:4-6, 11).