Does the Bible Give Any Precedent for Using the Title "Vicar of Christ?"
There is no precise Greek term for the word "Vicar." The closest one can find in Greek dictionaries is the term efimérios, but even that word is more properly rendered towards one who carries a priestly function. There is the word epitropou, which is defined as a steward or a guardian. Another term, used by St. Paul in 2 Corinthians 5:20, is presbeuomen. This word is defined as an ambassador, emissary, or representative, although normally in the context of an elder.
St. Paul writes, "We are therefore Christ’s ambassadors, as though God were making his appeal through us. We implore you on Christ’s behalf: Be reconciled to God."
This passage itself is very revealing. In its literal translation, it states: On behalf of Christ, therefore, we are ambassadors as God is urging through us.
In the Greek, "We are ambassadors" is in the first person plural, meaning he is speaking about his Apostolic authority and the authority in general of those sent by Christ as Apostles. We know this as well from the context.
In 2 Corinthians 3:1-3, St. Paul says, "Are we beginning to commend ourselves again? Or do we need, like some people, letters of recommendation to you or from you?... You show that you are a letter from Christ, the result of our ministry."
In 2 Corinthians 4:1, St. Paul is referencing himself and St. Timothy as having received their ministry due to the mercy of God: "Therefore, since through God’s mercy we have this ministry, we do not lose heart."
In 2 Corinthians 5:11-12, St. Paul again uses the "we" in contrast to the "you" who are the Corinthians, when he writes, "What we are is plain to God, and I hope it is also plain to your conscience. We are not trying to commend ourselves to you again, but are giving you an opportunity to take pride in us, so that you can answer those who take pride in what is seen rather than in what is in the heart."
So when St. Paul says "We are ambassadors," he is speaking principally about himself and Timothy and all those with Apostolic authority. It is interesting that he says they are ambassadors, emissaries, representatives of Christ.
Collins Dictionary defines "vicar" as a person who acts in place of another; substitute; a person who is authorized to perform the functions of another.
Even if we wish to make use of a wider application to 2 Corinthians 5:20, saying it is speaking to all Christians, this is still a stunning admission. It would be teaching that all of us are ambassadors and representatives of Christ.
In Luke 10:8, Our Lord authorizes the Seventy Two disciples to perform His functions: "When you enter a town and are welcomed, eat what is offered to you. Heal the sick who are there and tell them, ‘The kingdom of God has come near to you.’"
Some argue that the only true Vicar of Christ is the Holy Ghost, since Our Lord promises to send Him to the Church in John 14:26 and John 16:13. But who is Our Lord speaking to directly in these passages? He is speaking to His Apostles. The Holy Ghost will be sent to them, to lead them into all truth, so they can fulfill the commission of Christ to them in Matthew 28:18-20 to go and teach the whole world. We see this initiated in Acts 2 at Pentecost, when the Holy Ghost descends on the Apostles, and St. Peter goes out to boldly proclaim the Gospel and they begin baptizing converts.
We see the Holy Ghost at work in this regard in Acts 15:28 at the Council of Jerusalem, where St. Peter and the Apostles (and their successors, such as St. Matthias) had to settle a doctrinal dispute. "For it hath seemed good to the Holy Ghost and to us." The Holy Ghost guided them and worked with them. This is how the Holy Ghost operates, and this then shows us why St. Paul can say that he and St. Timothy are ambassadors of Christ, or in another sense, vicars of Christ.
The Holy Ghost is given to individual Christians so that we can live holy lives through utilizing His gifts to us, as we learn in Galatians 5:22-24. We receive the Holy Spirit for sanctification, so we can be holy. Not so we can each try to determine dogmatic truths pertaining to faith and morals, since that is His role specifically with the successors of St. Peter and the Apostles, as we see in Acts 15.
Do we see Jesus speaking to His Apostles and designating them to act as His representatives and to continue His ministry? Yes, in many places.
Matthew 10:40 He who receives you receives me, and he who receives me receives him who sent me.
Matthew 16:19 I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.
Matthew 18:18 Whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.
John 13:20 Truly, truly, I say to you, he who receives any one whom I send receives me; and he who receives me receives him who sent me.
John 20:23 If you forgive the sins of any, they are forgiven; if you retain the sins of any, they are retained.
Luke 10:16 Whoever listens to you listens to me. Whoever rejects you rejects me. And whoever rejects me rejects the one who sent me.
Jesus even applies such designations to a wider audience in other passages.
Matthew 25:40 Truly, I say to you, as you did it to one of the least of these my brethren, you did it to me.
Mark 9:37 Whoever receives one such child in my name receives me; and whoever receives me, receives not me but him who sent me.
We also have a plethora of passages where disciples of Jesus are spoken about as being explicitly identified as being one with Him.
2 Corinthians 1:5 For just as we share abundantly in the sufferings of Christ, so also our comfort abounds through Christ.
Galatians 6:17 From now on, let no one cause me trouble, for I bear on my body the marks of Jesus.
Philippians 3:10 I want to know Christ—yes, to know the power of his resurrection and participation in his sufferings, becoming like him in his death.
Galatians 2:20 I have been crucified with Christ and I no longer live, but Christ lives in me.
Colossians 1:18 And he is the head of the body, the church.
Colossians 1:24 Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in Christ’s afflictions for the sake of his body, that is, the church.
1 Peter 4:13 But rejoice insofar as you share Christ’s sufferings.
So, if the office of the Pope, the successor of St. Peter as Bishop of Rome, is meant to represent Christ to the world in a visible way, then giving such an office an honorary title of designation such as "Vicar of Christ" is not scandalous or blasphemous. Far from it. The roots are all in the Bible. In this regard, who is being more biblical? The Christians or the Protestants?
St. Paul called himself, and St. Timothy, ambassadors for Christ. Synonymously, they are calling themselves vicars of Christ. We are the Body of Christ. Thus, we continue His work in the world. And so if this is true of us, how much more so ought an honorary title of designation fittingly apply to an Office which serves to continue the unique ministry entrusted to St. Peter and his successors?
The office of Bishop of Rome carries with it the keys to the kingdom of Heaven. Thus, applying an honorary title such as "Vicar of Christ" is sensible since he, too, in a more profound way, must continue to mission of Our Lord. It is not dependant on the man holding the position, since the honorary title applies to the office as a whole. We all pray that the one occupying it lives up to such a high call.