Jesus said "I will build my church, and the gates of hell shall not prevail against it."
"Never will I leave you. Never will I forsake you." "I will be with you always, even to the very end of the age."
These are the promises of God to His people, to those who are in Christ. God is indeed faithful to all of His promises, even in death we come out victorious.
God has not and never did promise America, or any nation that He would build her and keep her from collapse.
God's promises are not for The United States, or even the nation of Israel.
God's promises, all of His promises are always yes in Christ Jesus, to
His glory, not to a nation's or individual's glory.
America is not assured of her future, only Christ's people are.
However, that being said, wisdom teaches that it goes far better for a nation that practices a morality that is in line with His word than contrary to it.