In the encyclical “Mystici Corporis” (1943), Pope Pius XII declared: “To describe this true Church of Christ – which is the Holy, Catholic, Apostolic, Roman Church – there is no more noble, none more excellent, none more Divine, than the expression, “the Mystical Body of Christ”.
The Mystical Body of Christ is the whole visible society in communion with the pope, the Church of Christ.
Eph. 1:22 – he has put all things under his feet and has made him the head over all things for the church…
Col. 1:18 – He is the head of the body, the Church.
Rom. 12:4-5 – For as in one body we have many members, and all the members do not have the same function, 5 so we, though many, are one body in Christ, and individually members one of another.
Col. 2:19 – and not holding fast to the Head, from whom the whole body, nourished and knit together through its joints and ligaments, grows with a growth that is from God.
Eph. 4:15 – Rather, speaking the truth in love, we are to grow up in every way into him who is the head, into Christ…
Eph. 5:30 – Therefore, putting away falsehood, let every one speak the truth with his neighbor, for we are members one of another.
1 Cor. 12:12-3 – For just as the body is one and has many members, and all the members of the body, though many, are one body, so it is with Christ. 13 For by one Spirit we were all baptized into one body–Jews or Greeks, slaves or free–and all were made to drink of one Spirit.
1 Cor. 12:27 – Now you are the body of Christ and individually members of it.
1 Cor. 6:15 – Do you not know that your bodies are members of Christ?
St. Ignatius of Antioch [AD 107] I will [send you further doctrinal explanations] especially if the Lord should reveal to me that all of you to a man, through grace derived from the Name, join in the common meeting in one faith, and in Jesus Christ, who was of the family of David according to the flesh, the Son of Man and the Son of God, so that you give ear to the bishop and to the presbytery with an undivided mind, breaking one Bread, which is the medicine of immortality, the antidote against death, enabling us to live forever in Jesus Christ. (Letter to the Magnesians, 22, 2)
St. Augustine of Hippo [AD 391-430] If, then, you wish to understand the Body of Christ, hear the Apostle speaking to the faithful: “You, however, are the Body of Christ and His members”. If, therefore, you are the Body of Christ and His members, your mystery is presented at the table of the Lord: you receive your mystery. To that which you are, you answer: “Amen”; and by answering, you subscribe to it. For you hear: “The Body of Christ!” and you answer: “Amen!” Be a member of Christ’s Body, so that your “Amen” may be the truth.
St. Irenæus of Lyon [AD 180-199] In the Church, God has placed apostles, prophets and doctors, and all the other means through which the Spirit works; in all of which none have any part who do not conform to the Church. On the contrary, they defraud themselves of life by their wicked opinion and most wretched behavior. For where the Church is, there is the Spirit of God; and where the Spirit of God, there the Church and every grace, The Spirit, however, is Truth. (Against heresies, 3, 24, 1)