There’s plenty of discussion around why Catholics call priests father but doesn’t the Bible say that no one but God is holy? Why do Catholics call the pope holy?
The answer is simple once we know what “holy” means. Some believe that it means to be sinless like God is sinless, and if that were true the pope certainly would not be holy.
In Exodus, Moses is told to remove his sandals because he is on “holy ground”. The Ark of the Covenant (the box that held Aaron’s staff, the stone tablets, and manna) was called the “Holy of Holies” Israel was a “holy nation, a people set apart” and this explains what holiness is.
Ground, boxes, and nations cannot be sinless, but they can be set apart or reserved for a sacred purpose. That’s what holiness is; being reserved for service to God. In that sense, only God is holy, just like only God is our father. All holiness comes from him and all creation comes from him. He gives us ways to participate in his creative spirit, and he gives us ways to participate in his holiness.
Whenever the purpose of people, objects, or places are consecrated for God, they become holy in their purpose. The Holy Father is holy because he is the Vicar of Christ, he is set apart for the divine purpose of leading the Church on earth. A chalice is holy because it is set apart to hold the blood of Christ. We are holy in that we were created with the purpose to know, love, and serve God. All things are holy to the extent that their existence is to serve the Lord.