It is really sad for me to see how many Roman Catholics I have known personally to question the Bible, saying that they need more than the Bible but they suddenly call the Pope as "Holy Father" which their reasons can be found in Catholic Answers:
Only God is holy by his very essence; however, by a person, place, or thing’s association with God, it too can be called holy. To be called holy is to express the idea of consecration, that someone or something belongs to God. That is why the Bible can call many persons, places, and things holy.
In Genesis 28:16, the place God appears is "holy." In Exodus 19:6, God tells the Israelites through Moses, "and you shall be to me a kingdom of priests and a holy nation." God’s dwelling place in the Tabernacle is "holy" (Ex 28:43), as is the city of Jerusalem (Is 48:2). Even a goat, the victim of sacrifice to God, is called "holy" in Leviticus 10:17.
After Christ’s death and resurrection the Christians called themselves and each other "holy ones" or "saints," called by God to be his (Rom 1:7). In 1 Peter 1:16 we read, "it is written, ‘You shall be holy, for I am holy.’"
Since we are his holy people, and his people are the Church, it is fitting that the head of his holy people be called Holy Father—not because of his own merit, but because Christ died for him and for the Church that he leads on earth.
The argument above really tries to justify calling the priest "father" and the Pope as "holy father". It is true that Christians are to be holy as Christians are holy. The Greek word for holy used in John 17:11 is hagie (ἅγιε). 1 Peter 1:16 also uses two words for holy meaning hagioi (Ἅγιοι) and hagios (ἅγιος). It is saying, "Be ye holy (hagioi) for I am Holy (hagios)." One talks about divine holiness and Christ called God the Father as Holy (hagie) while the command to be holy is all about conforming to the image of Christ. Christians are called to be holy (hagioi) but only God is truly holy (hagios).
Christians have imputed holiness which leads to a changed life but only God is truly holy in the divine sense. To call the Pope as Holy Father is really blasphemous because nobody was ever called as such but God. Christians are called to be holy or separated from the world but they are not called to be holy in the sense that they possess the divine holiness that only God alone has. Only God is divinely holy while Christians only have holiness in the sense by God's declaration.