Q1) How do you know if someone is truly a saint if man is giving him that title?
The most literal definition of a saint is just a person who is holy and set apart by God for his Kingdom.
A saint is defined differently by catholics and protestants. I am careful when considering catholic theology to make sure what they preach is consistent with scripture.
It seems that a catholic has an understanding of what makes a saint a saint that is not defined based on scripture
In Catholic theology, the saints are in heaven. In the Bible, the saints are on earth. In Catholic teaching, a person does not become a saint unless they are “beatified” or “canonized” by the Pope or prominent bishop. In the Bible, everyone who has received Jesus Christ by faith is a saint. I Catholic practice, the saints are revered, prayed to, and in some instances, worshipped. In the Bible, saints are called to revere, worship, and pray to God alone.
The idea of the word “saints” is a group of people set apart for the Lord and His kingdom. There are three references referring to godly character of saints: “that you receive her in the Lord in a manner worthy of the saints …” (Romans 16:2). “For the equipping of the saints for the work of service, to the building up of the body of Christ” (Ephesians 4:12). “But immorality or any impurity or greed must not even be named among you, as is proper among saints” (Ephesians 5:3).
Therefore, scripturally speaking, the “saints” are the body of Christ. All Christians are considered saints. All Christian are saints—and at the same time are called to be saints. First Corinthians 1:2 states it clearly: “To the church of God in Corinth, to those sanctified in Christ Jesus and called to be holy…” The words “sanctified” and “holy” come from the same Greek root as the word that is commonly translated “saints.” Christians are saints by virtue of their connection with Jesus Christ. Christians are called to be saints, to increasingly allow their daily life to more closely match their position in Christ. This is the biblical description and calling of the saints.
Q2) Is the pope supposed to be a rep of Jesus on earth?
A2) All of us who believe in the Word of God are supposed to represent Jesus Christ on earth. So yes, the Pope is expected to live accordingly, and so are you and I. This manner of lifestyle is what sets us apart and makes us saints, wholly holy and submissive to our Lord.