I guess I shouldnt say this because its a question and andwer thread, but elders are very biblical. but what you said does bring up a question, what makes you think the pope is holy (manifestly perfect)...or are you just using that in the context as in we are all made holy to God?"Holy Father" and "Your Holiness" are formal greetings for the pope. These are the traditional ways of referring to him. Granted, not every pope in the history of the Church has lived up to the title, but the vast majority of them have, and our present pope definitely has. Regardless, the greeting is used not so much because the pope deserves it but because he holds a position in the Church that demands respect. Just like we respect the position of a judge in our judicial system by greeting him as "Your Honor," we greet the pope by saying "Holy Father" or "Your Holiness."
The pope in particular, in virtue of the sacrament of Holy Orders he has received, was forever changed by God. An indelible mark was placed on his soul and he was set apart by God to be a minister to His people. In Scripture we see that men are constantly commanded to respect and obey the elders (Gk. presbuteros, or "priests") of the church (1 Thes 5:12-13; 1 Tim 5:17; Heb 12:9; 13:7,17; 1 Pet 5:5), and those who reject their authority are looked down upon and judged harshly (2 Pet 2:10-12; 1 Jn 4:6; 3 Jn 1:9-11; Jude 1:8-10). He who takes up Korah's rebellion will perish in it (Jude 1:11; cf. Num 16:30-35).