"Nations most often fall from within, and this fall is usually due to a decline in the moral and spiritual values in the family. As families go, so goes a nation."
No, nations usally fall when they are attacked by another more powerful nation. They can, however, fall from within but it's not 'most often' that they do fall that way.
However, a nation that is moral and upright will be far less vulnerable to its enemies than one which has suffered this sort of decay from within.