"Righteousness exalts a nation but sin is a reproach (lit. a disgrace) to any people."
Proverbs 14:34

Better than so-called "Christian Nationalism" is national righteousness, aka "a righteous nation." Righteousness is the opposite of sin (lawlessness 1 John 3:4) and therefore is the application of God's Law among the nations: "By me kings reign, and rulers decree justice. By me princes rule, and nobles, all who judge rightly." (Proverbs 8:15-16).
"For the Lord is righteous, He loves righteousness; The upright will behold His face."
Psalm 11:7
"He loves righteousness and justice...."
Psalm 33:5
"You have loved righteousness and hated wickedness; Therefore God, Your God, has anointed You With the oil of joy above Your fellows."
Psalm 45:7
"Give the king Your judgments, O God, And Your righteousness to the king’s son."
Psalm 72:1
"Righteousness and justice are the foundation of Your throne"
Psalm 89:14; 97:2
"How blessed are those who keep justice, Who practice righteousness at all times!"
Psalm 106:3
"Your righteousness is an everlasting righteousness, And Your law is truth."
Psalm 119:142