Answer
The term "vicar" comes from the Latin word vicarius, which means "instead of." In the Catholic Church, the vicar is the representative of a higher-ranking official, with all of the same authority and power that that official has. Calling the pope the "Vicar of Christ" implies that he has the same power and authority that Christ had over the church. The title is derived from Jesus’ words in John 21:16-17 to Peter, "Feed my lambs . . . Take care of my sheep." This, according to Catholic reasoning, defines Peter as the Prince of the Apostles, the first pope, and fulfills the words of Jesus in Matthew 16:18-19 (calling Peter the rock upon which Jesus will build His church).
For a better understanding of whether or not it is biblical to consider that a mere man is the representative of Christ, we turn to the pages of Scripture to find out what it says about Jesus’ role in our lives, when He walked the earth and what He continues to do right now. The letter to the Hebrews draws the comparison between Jesus and the high priest Melchizedek (Genesis chapter 14) and contrasts this with the old Levitical priesthood. The question posed is, if perfection could be obtained by following the law, why was another priest to come (Hebrews 7:11)?
The writer says, “For it is clear that our Lord descended from Judah, and in regard to that tribe Moses said nothing about priests. And what we have said is even more clear if another priest like Melchizedek appears, one who has become a priest not on the basis of a regulation as to his ancestry but on the basis of power of an indestructible life. For it is declared ‘You are a high priest forever in the order of Melchizedek.’ The former regulation is set aside because it was weak and useless (for the law made nothing perfect), and a better hope is introduced, by which we draw near to God” (Hebrews 7:14-19).
This makes Jesus superior to the priests, and more importantly, the high priests. This is the key text: “Now there have been many of those priests, since death prevented them from continuing in office; but because Jesus lives forever, He has a permanent priesthood. Therefore, He is able to save completely those who come to God through Him, because He always lives to intercede for them” (Hebrews 7:23-25).
This means that Jesus is our high priest forever. Since He is "holy, blameless, pure, set apart from sinners, [and] exalted above the heavens" (Hebrews 7:26), He is unlike other priests in that He "does not need to offer sacrifices day after day, first for His own sins, and then for the sins of the people. He sacrificed for their sins once and for all when He offered Himself" (Hebrews 7:27). Men are appointed by the Law, and men are weak. But the Son was appointed by the New Covenant, and He has been made perfect forever (Hebrews 7:28). The ministry of Jesus is superior to the old, and it is founded on better promises (Hebrews 8:6).
The Bible says of Jesus that there is no other name by which men can be saved (Acts 4:12). There is only one mediator between God and men, and that is Jesus Christ (1 Timothy 2:5). We can now see that there is no biblical foundation for claiming to be a representative of Christ on earth. No man could do what Christ has done, or what Christ is now doing on behalf of humankind. But the title of vicar also carries with it another implication: the bearer has the same jurisdictional power of the official he represents. In Matthew 16:18, Jesus Christ is the one who says He will build His church; He never delegates this power. By claiming the title of Vicar of Christ, the reigning pope is, in fact, promising to do what Christ promised.
Jesus does indeed predict a “vicar” in the sense of a “replacement” for His physical presence here on earth. However, this “vicar of Christ” is not a priest, high priest, bishop, or pope. The only biblical “Vicar of Christ” is the Holy Spirit. John 14:26 declares, “But the Counselor, the Holy Spirit, whom the Father will send in my name, will teach you all things and will remind you of everything I have said to you.” John 14:16-18 proclaims, “And I will ask the Father, and He will give you another Counselor to be with you forever — the Spirit of truth. The world cannot accept Him, because it neither sees Him nor knows Him. But you know Him, for He lives with you and will be in you. I will not leave you as orphans; I will come to you.” The Holy Spirit is Christ’s “replacement” on the earth. The Holy Spirit is our Counselor, Teacher (John 14:26), and guide into all truth (John 16:13).
In claiming that the pope is the “Vicar of Christ,” the Catholic Church rejects the sufficiency and supremacy of Christ’s priesthood, and grants to the pope roles that Christ Himself declared would belong to the Holy Spirit. It is therefore blasphemy to ascribe to the pope the title of “Vicar of Christ.”