The doctrine of the Two Kingdoms is helpful in figuring this out. Basically this doctrine tells us that there are two very different kingdoms and that a Christian lives in both of them. The kingdom of the left, as it is called, is the kingdom of government. The government has the job to wield the sword to protect its citizens and to preserve society from anarchy (Romans 13:1-7). The kingdom of the right is the kingdom of the Church. This kingdom is characterized as a kingdom of righteousness, peace and joy (Romans 14:17). The marks of this kingdom are found in the Sermon on the Mount and include such things as meekness, hungering after righteousness, mercy, purity of heart and love for our enemies (Matthew 5). Unless a Christian actually is working for the government, his role in the kingdom of the left is to abide by the laws of the land (unless they directly violate the laws of Christ) and in a democracy to vote for those who best represent our values. It is not in our sphere of influence to decide who or who does not get into our country. The government has to make those decisions, knowing that they have to balance out compassion and safety. This is a difficult thing to do and they need our prayers.
On the other hand, as citizens of the kingdom of the right, we have a completely different way of approaching this issue. Jesus has called us to love even our enemies and to seek to lead them to Himself. We don't decide who comes here but we are commanded to love those who do. There is an example of this in Germany. There the government decided to take in hundreds of thousands of refugees. They were coming regardless of what members of the Church thought about it. But some in the Free Lutheran Church (the orthodox/Biblical Lutherans) decided to receive these refugees as Jesus would have them receive them. By their acts of compassion many of these refugees began to realize that Christianity was a far superior faith to their own. Hundreds have already been won to Christ and have been baptized. One congregation has grown from 160 to well over 600 and another 100 are being prepared for baptism, even as we speak. The German members of the congregation are even growing in their own faith as they watch how these new believers receive the Word and the Sacraments with such joy.
I don't know what will be the final outcome of the debate over whether or not our government receives these people into our country but I do know that if they come we must reach out to them with the love of Christ and show them that He is the only way to the Father.