For as the body is one and has many members, but all the members of that one body, being many, are one body, so also is Christ. For by one Spirit we were all baptized into one body—whether Jews or Greeks, whether slaves or free—and have all been made to drink into one Spirit. For in fact the body is not one member but many.
Now you are the body of Christ, and members individually.
The First Epistle of St. Paul to the Corinthians 12:12-14, 27
The Church is a single body made up of many members. It is impossible for a Christian to be in the Church and separate from its other members. We can be in the Church or out of the Church, but we cannot come and go as we please. If we are in the Church we are unified with her totality. We are one.
Joining the Church does not negate an individual’s personality. Saint Paul exalts diversity in 1 Co. 12. The Holy Spirit does not disperse gifts equally. He gives them as He pleases. Instead of questioning His choices or envying another’s gifts, members are to strive to become the person God intended which is a life long endeavor. It is impossible apart from the love and grace of God.
And He Himself gave some to be apostles, some prophets, some evangelists, and some pastors and teachers, for the equipping of the saints for the work of ministry, for the edifying of the body of Christ, 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.
The Epistle of St. Paul to the Ephesians 4:11-16
The Church is the body of Christ. If He died for humanity when we were estranged from Him, how much more will He do for those who are members of His body? The fullness of God is found only in the Church. There is no need that has not already been filled. This fullness and completeness is known as catholicity.
What, then, shall we say in response to these things? If God is for us, who can be against us? He who did not spare his own Son, but gave him up for us all—how will he not also, along with him, graciously give us all things?
The Epistle of St. Paul to the Romans 8:31,32