Scripture identifies only one who acts as Christ's representative on earth: the Holy Spirit. Jesus told His disciples, "I will ask the Father, and he will give you another Helper, to be with you forever" (John 14:16). The Greek parakletos (Helper, Advocate, Comforter) is the one who takes Christ's place after His ascension. Christ is the sole head of the church (Ephesians 1:22), and He exercises His headship through His Spirit and His Word, not through a human successor. No apostle ever claimed to be Christ's vicar; Peter called himself a "fellow elder" (1 Peter 5:1), not the Vicar of Christ.
A substitute in office; one who performs the functions of another.
VIC'AR, n. [L. vicarius.] A substitute in office. In the church of England, the incumbent of an appropriated or impropriated benefice. Webster understood vicar as a deputy — one who acts in another's stead. The Roman claim that the pope is Christ's vicar on earth raises the question: did Christ appoint a permanent human substitute, or did He send His Spirit?
• John 14:16-17 — "I will ask the Father, and He will give you another Helper, to be with you forever, even the Spirit of truth."
• Ephesians 1:22-23 — "He put all things under his feet and gave him as head over all things to the church."
• 1 Peter 5:1 — "I exhort the elders among you, as a fellow elder and a witness of the sufferings of Christ."
The title "Vicar of Christ" usurps a role that belongs to the Holy Spirit alone.
The papal claim to be the Vicar of Christ is arguably the most audacious human claim in the history of religion. It asserts that one man stands in the place of Christ on earth, speaks with His authority, and governs His church. The Reformers recognized this for what it is: a usurpation of Christ's unique headship and the Spirit's unique role. Christ did not leave His church in the hands of a human successor; He sent the Holy Spirit to guide, convict, and empower. The claim of any man to be Christ's vicar is not humility but hubris — a claim that places a sinful human being in the seat that belongs to God alone.
• "Christ's vicar on earth is the Holy Spirit, not a man in Rome. Jesus said He would send another Helper — and He did."
• "Peter called himself a fellow elder, not the Vicar of Christ. The papal title has no foundation in Scripture or in the practice of the apostles."