How is it that taking on unaccounted numbers of refugees, distinctively "Christian". Christianity does not place on any nation an absolute, unqualified moral obligation to allow the entry of refugees. A country may legitimately consider any number of issues respecting the entry of any category of refugees. If a country refuses to allow the entry of certain categories of people onto its shores it has not deprived anyone's rights, nor has it committed an injustice. The refusal not to allow certain people entrance is in no way an immoral act. These are prudential matters and you may disagree with a specific decision, but you cannot claim to do so on "Christian" grounds. 

It is wrong and unfair,  to burden any nation with the stresses and costs associated with the imposition of alien  nationals. We have seen what liberal government policies respecting immigration has produced,  in Europe, and if America wants to stop it, it has every right to do so.