Now, I don't equate America with Christianity or the Kingdom. Certainly the church was not destroyed by Rome or the Jews. The only real way to destroy the church is from within. Sin.
And, the church is being systematically destroyed by carnal sin and apathy. Outside of the church walls, it's hard to tell distinguish between the church and the world.

America, likewise, will be destroyed from within. No country can attack us and win. We are, though ,being destroyed by Liberalism and an asanine desire for globalism.
This gloablism will be accomplished with the destruction of America and the Anticrhrist will come forth.
In the end, sin will cause the destruction of America and our turning wholesale away from God.