America has always been an idea in search of an ideal. No external fource can destroy us. But internal forces can. It has been that way with empires throughout history. Ancient Rome became corrupt, and fell from within before invading armies toppled it from without. The British Empire was over-extended and colonialism, the enemy of freedom, was a bad idea.
America's strength has been in its faith in God. He liberates from sin through Christ and this liberation leads to a desire for freedom in our temporal kingdom and to share these ideals with others. If secularism, materialism and selfishness replace God, we will go the way of those empires that have risen and fallen before.
It is God who is the true author of liberty -- in Christ if He is in our hearts. As the hymn goes, "Our father's God to thee, author of liberty, to thee we sing. Long may our land be bright, with freedom's holy light, protect us by thy might, great God our King."
I'm Cal Thomas in Washington.