'Papal supremacy' is the outcome of 'Papal infallibility'. It is the corrupt fruit of a corrupt tree.
Claims to supremacy are very wide. It is asserted with regard to both politics and religion. Temporal and spiritual supremacy is the proud boast of Antichrist. The matter of spiritual supremacy is the more serious. The decree of Pope Boniface VIII states: "Temporal authority must be subject to spiritual power." Pius IX, writing to the Emperor of Germany on 7th August, 1873, said: "Every one who has been baptized belongs in some way to the Pope."
Lest any ecumenist should say that Rome's position has changed, bear in mind the following excerpts from A Catechism of Catholic Doctrine (Revised edition, 1985): "The Pope is the spiritual father of all Christians. […] The Pope is the Shepherd and Teacher of all Christians." What is this, if it is not a claim to supremacy?
Claims to supremacy are not only wide but wicked. They gender deception by turning souls away from Christ to trust in a man, all the while with the belief that this will bring salvation.
Boniface VIII decreed: "It is necessary for everyone who is to be saved to be subject to the Roman Pontiff"; but Christ said: "I am the way, the truth and the life. No man cometh unto the Father, but by me." The claims to supremacy are wicked because they are an attempt to rob God of His glory. The blasphemous character of this boasted pre-eminence is seen in the divine name the Pope takes to himself. He is called 'Holy Father'. The Council of Pisa described him thus: "The most holy and blessed one […], the Lord of the Universe." The only true and living God will not smile on such arrogance. Isaiah 42:8: "I am the Lord: that is my name: and my glory will I not give to another […]."
Papal aspirations to supremacy are wrong. They are based upon a wresting of the Scriptures. For example, concerning Christ's words to Peter (who, it is said by Rome, was the first in the line of the Popes) in John 21:15-17: "Feed my sheep. […] Feed my lambs", a most unnatural explanation is given. Rome construes the command as a commission to Peter to take charge of the whole church, pastors and people, whereas the injunction given to him is also given to all pastors: "[…] feed the church of God." (Acts 20:28; 1 Peter 5:2.)
Ideas of Papal absolutism have also been advanced by forgeries - for example, the Donation of Constantine, purported to have been written by him and conferring vast privileges on the Church of Rome. It was published for the first time in the middle of the eighth Century. Attached was the fable that it was granted by Constantine on the occasion of his being baptized by Pope Sylvester as a grateful return for his having been cured of leprosy by the baptismal water. The evidence of history proves that Constantine was never afflicted with leprosy and was not baptized until he was on his deathbed.