Thinking about immigration gives the Christian some trouble. He must begin thinking nationally and Christianly at the same time. He must bring together in his mind what his theology purportedly divides: Christianity and nation.
Whatever his stance on immigration, the sincere Christian wants the nation to act a certain way: Christianly. This is true of war, healthcare, and a host of other issues forced upon the him by the pressing world. The Christian desires the nation to act Christianly, yet he does not believe that nations are predicated upon Christianity or its ethic. Or to put it another way: he holds that the nation ought to act Christianly but that it need not be Christian to do so.
The problem is apparent, and there are a few ways to go about this. Some hold that one must think of Christian and nation at the same time and in some legitimate, tangible, actual connection. For them the nation would be obligated to obey Christ because it is under his authority, etc. to do so. In this sense, it is obligated to be and act Christian. Others demand the nation enact Christlike legislation without having to confess Christ in its laws and constitutions. For them there is perhaps some middle ground we can all agree upon. Still others hold that the benefits of Christianity are socially accessible without recognition and confession of the sacrifice that purchases them. For them Christianity is mere humanist moralism baptized in Christian language.
If there is another way, I cannot imagine it at this point. Yet, I think these points illustrate a problem in the mind of the 21st century Christian: should his religion remain private or should it come out and play?