God "judges" the nations by His Will, by the action of His Statutes, Laws, Commandments, i.e. instructs, teaches the Truth, leads people to a life of righteousness, establishes justice, corrects those who have gone astray, punishes those who have violated His Commandments.

 "Judge" Christ-Jesus Christ, who perfectly knew and fulfilled the Will of God and His Commandments, is therefore a "Judge," that is, a man who has the right to determine good and evil, Truth and unrighteousness and to judge man's deeds, whether they are righteous or sinful.  

"Judge" Man is a righteous man who knows and obeys God's Commandments, who rightly determines Good and Evil, who distinguishes a righteous life from a sinful one, who reproves iniquity.

Negative Meaning.

"Judge" is a person who judges another on the basis of sinful morals, established traditions, beliefs, religious dogmas, political ideologies, sinful worldviews and lifestyles, wrongly perceiving and undeservedly condemning the righteous deeds of others.