Borders were ordained by God even before the fall of Adam and Eve.
God separated that nations/bloodlines and established boundaries for them.  “No Nations No Borders” is a cry of rebellion from the anti-Christs — it is a call from the evil one to return to Babel.

Everyone expects their own fenced back yard to be respected, not to be shared with everyone; why then are national borders/fences seemingly a strange concept?

The invasion of a Christian nation by foreigners is a curse that comes upon a people that turns away from Jesus Christ to serve foreign gods.