Donald Trump wants to make America great again. This is problematic, because America has never really been great. It has alwasy had a dark underbelly that belies greatness.
Anyway, only the church and the kingdom can be truely great. And the kingdom of God is not a nation state.
Of course, America is not a nation state. It has always been a multi-national state. Unfortunately, a multi-national state has a tendency to fly apart. This is partly what the presidential election was about.
A multi-national state needs a common enemy to keep it united: Nazi Germany, the Soviet Union, Iran, ISIS. Some are trying to recycle Russia for this unifying role, but it is too weak to be a serious enemy.
When its enemies are defeated, the only thing that can hold a multi-national state together is a political dictator. That is why most multi-national states eventually become an empire.