One body in Christ…

By nature, each one of us is enclosed in his own personality, but supernaturally, we are all one. We are made one body in Christ, because we are nourished by one flesh. As Christ is indivisible, we are all one in him. Therefore, He asked His Father “that they may all be One as We also are one.
–Saint Cyril of Alexandria (378-444)

The indestructible church…

The Church has ever proved indestructible. Her persecutors have failed to destroy her; in fact, it was during times of persecution that the Church grew more and more; while the persecutors themselves, and those whom the Church would destroy, are the very ones who came to nothing. . . .Again, errors have assailed her; but in fact, the greater the number of errors that have arisen, the more has the truth been made manifest. . . . Nor has the Church failed before the assaults of demons: for she is like a tower of refuge to all who fight against the Devil.
–Saint Thomas Aquinas (1225-1274)

The Catholic Church is…

Just as in one man there is one soul and one body, yet many members; even so the Catholic Church is one body, having many members. The soul that quickens this body is the Holy Spirit; and therefore in the Creed after confessing our belief in the Holy Spirit, we are bid to believe in the Holy Catholic Church.
–Saint Thomas Aquinas (1225-1274)