Ephesians 4:13 until we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ, so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.
Paul did not command a structural or organizational unity, but a spiritual unity around a common faith. People are given spiritual gifts (they are equipped) for building up and equipping Christians to maturity in faith, knowledge, understanding, and intimacy with Jesus Christ. Remember Paul telling the Corinthians that they were still babies in faith and though they should be on solid food they were still infants on milk concerning things of God. Maturity in faith does not just happen. It must be cultivated, watered, and fed. Spiritual maturity, knowledge, understanding, discernment, and wisdom grow when the heart and mind and soul intentionally choose to deny self and worldly lusts, pleasures, and schemes but rather chooses to humbly surrender to the will of God, seeking and desiring to be led by Him, obeying, following, trusting, and relying on Him for the ever-growing and maturing want to honor and glorify Him in all that is thought, spoke, or action taken.