Reaganite in NYC (in the comments area) raises two very important points about how faith can be reflected in public life. First he says there’s no conflict between an emphasis on personal (John 3:16) or collective salvation (Matthew 25). Reaganite in NYC is absolutely right about that.
Politically, though, there has been a definite difference in emphasis between liberal and conservative Christians. Liberals invariably emphasize the latter, conservatives the former. Evangelicals have mostly emphasized personal salvation but are now in a moment when they’re considering how much to care about issues like poverty, AIDS and the environment.
His second point is there’s a difference between collective salvation and collectivism. That’s worth talking through. Reaganite makes the classic conservative case that you can be for helping others without employing state coercion:

“If my words and prayers cause a wealthy person to voluntarily share his goods with the poor, then my actions have contributed to that wealthy person’s salvation. That is an example of “collective salvation.”
If on the other hand I compel that wealthy person (via legislation to rewrite the tax code) to give up his goods — against his will — then I have done nothing to advance that wealthy person’s salvation. Nor have I advanced my own salvation, since the theft which I am cooperating with (via confiscatory taxation) is not morally licit even under the best of motives.”

I don’t tend to view all forms of taxation as immoral. By being part of society we agree that in exchange for the benefits of the state we pay taxes that support the parts we like and sometimes the parts with which we disagree. Liberals fume over having their hard-earned pay go to fund a war in Iraq they abhor. But because we have democratic elections, we are all agreeing to the idea that the laws created by the representatives we chose are not inappropriately coercive. The question then is not whether there’s going to be coercion – there is, because we voted for it – but what it should be for?
Helping stop starvation in Africa through federal taxdollars is indeed coercive, but is it really immoral? An increasing number of evangelicals who heretofore had viewed it as inappropriate are now saying that such collective action is deeply Biblical. Dr. Mohler and Dobson have a different emphasis. How evangelicals resolve this tension between emphasizing personal salvation and collective obligation will affect not only personal faith but politics.