Matthew 18:17 "And if he refuses to listen to them, tell it to the Church; and if he refuses to listen even to the Church, let him be to you as a Gentile and a tax-gatherer."

Jesus had just said in Matt 16 that He would build His Church (notice, singular, not plural). Now, note here, in Matt 18:17, that the Church is a *visible* institution, something we can tell things to, and which can be listened to. This verse shows that the Church can excommunicate those in sin (cf. 1 Cor 5:1-5). But only a visible institution can excommunicate those in sin. An invisible entity can do no such thing. Furthermore, it would make no sense to excommunicate a person who could simply go down the street to the next "church" and be welcomed. This would in no way "deliver such a one to Satan for the destruction of his flesh, that his spirit may be saved in the day of the Lord Jesus." (1 Cor 5:5) The visible Church is therefore *one* visible institution. To be excommunicated is not only to be excommunicated from the local congregation, but from the whole universal Church around the world, i.e. the Catholic Church.

Christ founded (Matt 16:18) a *visible* Church, and it is about this visible Church, this "pillar and bulwark of truth", that He says (Matt 16:18) that the gates of hell will not prevail against it. And it was this visible Church that we know was called the Catholic Church by the end of the first century. There was no other visible Church for at least a thousand years! Since Christ is talking about founding (Matt 16:18; 18:17) a visible Church, this Church had to come into existence at the time of the Apostles. But the only visible Church for the first 1000 years after Christ was the Catholic Church. Therefore, it follows that Christ was talking about the Catholic Church. Therefore it is the Catholic Church which is the "pillar and bulwark of truth", and against which the gates of hell will not prevail.

Consider another verse:

"And I have other sheep, which are not of this fold; I must bring them also, and they shall hear My voice; and they shall become one flock with one shepherd." (John 10:16)

Here Jesus is speaking to the Jews, and when He says "other sheep" He is referring to the Gentiles. The Gentiles began to be brought into the "one flock" when Peter (Acts 10) had the vision in Joppa of the sheet containing the 'unclean' creatures. As the vision concluded, the messengers from Cornelius knocked on the door, and Cornelius and his family became the first Gentiles to receive the Gospel and be brought into the "one flock". We see that Peter leads the Church to receive the Gentiles. This verse (John 10:16) supports Catholicism in three ways: first, by saying that there will be "one flock", second, by saying that there will be "one shepherd", and third by showing that the Church's actions and voice are Christ's actions and voice, for Christ had already ascended before Peter preached to Cornelius, and yet Christ says that He is doing it, and that it is His voice that the Gentiles will hear.

The "one flock" is the Church. As with my previous example, this is not referring to some "invisible" Church, but to the visible Church. In no place does the Bible ever talk about an "invisible" Church; that would be a gnostic notion of the Church. The Church is always described as a visible institution (as we saw in Matthew 18), hierarchically ordered as one body. There are not ten flocks, or thirty flocks or thousands upon thousands of flocks as Protestantism would imply; there is "one flock", i.e. one visible institution, ordered under the Apostolic college, whose head (after Christ's ascension) was Peter. The "one flock" is the Church, the body of Christ. Likewise, the "one shepherd" is also Christ, for Jesus Himself is the "good shepherd", and yet Jesus is not here advocating ecclesial anarchy, as if there must be no pastors ("pastor" just means shepherd) in the Church except Christ alone. That would be entailed by the "either/or" mentality. But Scripture is frequently "both/and". For example, that pastors have authority is not incompatible with Christ having all authority (i.e. the highest authority). Likewise, that Christ is ultimately the "one shepherd" does not mean that no other person can be the "one shepherd" in His stead. We know that Christ is the Rock (1 Cor 10:4), and yet Christ Himself names Peter "Rock". (Matt 16:18) This verse (John 10:16) should be understood in the light of John 21:15-17, where Jesus commissions Peter to "Shepherd My sheep". In John 21:15-17, Jesus is not contradicting what He says in John 10:16; He is fulfilling it. In John 10:16 Jesus teaches that the one visible Church (composed of Jews and Gentiles) will have one visible head. When Jesus ascended, He did not leave the Church without a visible head. It would make no sense to have a visible Church (i.e. Christ and the Apostles) with a visible head (i.e. Christ), and then for that visible head to leave that visible Church without a visible head. This is why the successor of Peter is presently called the "vicar of Christ", because he stands in the place of Christ as the "one shepherd" of the "one flock" (i.e. the Catholic Church), until Christ returns.