Self-Holiness (sanctification) is the other requirement for salvation besides confession of Jesus
Follow after peace with all men, and the sanctification without which no man shall see the Lord: Hebrews 12:14
Holiness is attained by keeping 100% of the commandments or rules in Moses and the Prophets and in the New Testament (Numbers 15:40, Luke 16:29-31).
Self-Holiness (sanctification) is the goal of the making of man and of the RIGHTEOUSNESS of Jesus
Jesus died in the place of man to make it possible for mankind to become holy, live holy, and die holy emulating Jesus because Jesus already paid for the penalty of the past sins of the men who came unto repentance to become a brand-new holy creature.
Ephesians 1:3-4 ASV
(3) Blessed be the God and Father of our Lord Jesus Christ, who hath blessed us with every spiritual blessing in the heavenly places in Christ: (4) even as he chose us in him before the foundation of the world, that we should be holy and without blemish before him in love:
So, It is not true that men cannot become holy because they are sinners by nature
Yes, all men are sinners but Jesus came to bring all men from being sinners to become new holy creatures upon repentance, if men manage to not go back to their previous sins or sin new sins.
Holiness is one of the commandments to pursue and to keep because it is the passport to free salvation. hebrews 12:14
A commandment of God must be carried out by men and not by Jesus for men. ‘Be ye holy!’ is one of the commandments to keep. As a commandment, mankind must keep and observe it and NOT believe that Jesus will keep the commandment of holiness for us.