In the sermon on the mount Christ said,

"If you love those who love you, what reward will you get? Are not even the tax collectors doing that? And if you greet only your brothers, what are you doing more than others? Do not even pagans do that?"

Christians that have an America first attitude are disobeying Christ because they are not doing more than what pagans do. The charge of Christ is one of love and self sacrifice and not just for your neighbor but also for those who hate us and are our enemies. Christians everywhere ought to advocate for policies that are in the interest of justice for all humanity and not to advocate for policies that maintain American power or what is in America's self interest.

I'm not even religious and I think that the world is more important than America because America is part of the world. Simple logic says to care for the whole and your care will repay you in what little you put into the whole because you are in the whole, right?

I'm not sure that most people get this, because I'm a utilitarian, so I think the most worth you can get from life is that which you do not suffer. If you don't share, you will still have to deal with the suffering of others. If you do share, you have less, but others suffer less... and do you really suffer more with less than the whole with less?

They should be more concerned with the world. America isn't even mentioned in the prophesies (how important can it be). And if you believe that we are on the last days because some prophecies have come true, think again. For example, One prophecy is that Israel would be reborn and an alliance of countries will attack it and those countries will be obliterated by the hand of God. So the natural way to think is that we should do nothing (not concern ourself with the world) and let God deal with it. The problem is that the prophecy does not say how many times Israel will be reborn. For all we know Israel may come and go multiple times and this isn't the last days. If you want the last days, then you have to actively participate in making it come true. This means that we have to be concerned about the world.

Wow, that was a wild ride after that first sentence ;)