America has forgotten how it became a great nation. We have confused the products of greatness with the cause of greatness. It is not her wealth, position, power or military might which has made her great. These are merely the results of the great foundation wherewith she was founded.
It makes me think of Romans chapter one which speaks of mankind worshipping the creation instead of the Creator.

Romans 1:20] For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:
[21] Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.
[22] Professing themselves to be wise, they became fools,
[23] And changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.

The Bible warns us not to put our trust in military might.
Psalms 44:[5] Through thee will we push down our enemies: through thy name will we tread them under that rise up against us.
[6] For I will not trust in my bow, neither shall my sword save me.

The Bible warns us not to trust in our wealth.
Psalms 52:[5] God shall likewise destroy thee for ever, he shall take thee away, and pluck thee out of thy dwelling place, and root thee out of the land of the living. Selah.
[6] The righteous also shall see, and fear, and shall laugh at him:
[7] Lo, this is the man that made not God his strength; but trusted in the abundance of his riches, and strengthened himself in his wickedness.

The Bible warns us not to trust in power,
Psalms 62:[7] In God is my salvation and my glory: the rock of my strength, and my refuge, is in God.
[8] Trust in him at all times; ye people, pour out your heart before him: God is a refuge for us. Selah.
[9] Surely men of low degree are vanity, and men of high degree are a lie: to be laid in the balance, they are altogether lighter than vanity.
[10] Trust not in oppression, and become not vain in robbery: if riches increase, set not your heart upon them.
[11] God hath spoken once; twice have I heard this; that power belongeth unto God.

The Bible warns us not to trust in our rulers.
Psalms 146:[1] Praise ye the LORD. Praise the LORD, O my soul.
[2] While I live will I praise the LORD: I will sing praises unto my God while I have any being.
[3] Put not your trust in princes, nor in the son of man, in whom there is no help.

The Bible warns us not to put our trust in lying words.
Jeremiah 7:[1] The word that came to Jeremiah from the LORD, saying,
[2] Stand in the gate of the LORD’s house, and proclaim there this word, and say, Hear the word of the LORD, all ye of Judah, that enter in at these gates to worship the LORD.
[3] Thus saith the LORD of hosts, the God of Israel, Amend your ways and your doings, and I will cause you to dwell in this place.
[4] Trust ye not in lying words, saying, The temple of the LORD, The temple of the LORD, The temple of the LORD, are these.

The Bible warns us not to trust in our brother.
Jeremiah 9:[3] And they bend their tongues like their bow for lies: but they are not valiant for the truth upon the earth; for they proceed from evil to evil, and they know not me, saith the LORD.
[4] Take ye heed every one of his neighbour, and trust ye not in any brother: for every brother will utterly supplant, and every neighbour will walk with slanders.

The Bible warns us not to trust in friends.
Micah 7:[1] Woe is me! for I am as when they have gathered the summer fruits, as the grapegleanings of the vintage: there is no cluster to eat: my soul desired the firstripe fruit.
[2] The good man is perished out of the earth: and there is none upright among men: they all lie in wait for blood; they hunt every man his brother with a net.
[3] That they may do evil with both hands earnestly, the prince asketh, and the judge asketh for a reward; and the great man, he uttereth his mischievous desire: so they wrap it up.
[4] The best of them is as a brier: the most upright is sharper than a thorn hedge: the day of thy watchmen and thy visitation cometh; now shall be their perplexity.
[5] Trust ye not in a friend, put ye not confidence in a guide: keep the doors of thy mouth from her that lieth in thy bosom.

The Bible warns us not to even trust in ourselves.
2Corinthians 1:[8] For we would not, brethren, have you ignorant of our trouble which came to us in Asia, that we were pressed out of measure, above strength, insomuch that we despaired even of life:
[9] But we had the sentence of death in ourselves, that we should not trust in ourselves, but in God which raiseth the dead:

Whether it be a man or a nation, whenever they forget Who made them great and begin to think the things which were a product of their greatness is what made them great they are in for a fall.

Psalms 9:[17] The wicked shall be turned into hell, and all the nations that forget God.