I've heard things like, "We want a return to a Christian nation" and such things. Now, of course, that would be good for the Kingdom if America did in fact return to being a nation where Christianity is pure, and truly sought after by millions of people. Currently a lot of Christianity has some corrupted views, or tends to be a stale, "yeah I go to church", kind of Christianity.
Yes, I think it would be great if America were re-Christianized,in a sense (not that it was ever 100% Christian, but it was built on Judeo-Christian principles). However, I think that when we have that as our goal, some things go missing. If we are aiming to bring Christianity back to our entire country, it can be quite easy to forget our one friend who we know isn't Christian. I've seen a meme saying something like "Duck Dynasty: Bringing Christianity back" or somethingish like that. However, I would bet that the Robertson family has someone close that they know who doesn't believe in Jesus, and probably a few whose faith extends to going to church on sunday morning.
A quote from Bryan Davis from Tears of a Dragon that I think is perfect for this topic: "If it is in our power to save lives, shouldn't we do it? Shouldn't we try to save [captive] and trust God to save the world? Shouldn't we try to free a wife and daughter and trust God to liberate the rest of mankind?" ... "God has long been in the business of providing the savior the world needs. Our part has always been to reach out to one soul at a time."
The general idea the way I'm using it being God can deal with his plans for America. Our goal should be to find those people around us who need Him, and through our ministry to our friends, God can spread to the nation.
To summate, God can save America. Let's focus on those closer to us.