In Exodus 22:19 it says, "Anyone who has sexual relations with an animal must be put to death." and 20 "Whoever sacrifices to any god other than the Lord must be destroyed."
Lev. 19: 27 says, "Do not cut the hair at the sides of yur head or clip off the edges of your beard."
Do you follow those rules as well? Or are you selective when it comes to following the rules of the OT? I could give you more examples, but I think you get the idea. If you shave are you going against God? Of course not. THe point is as I said before.
The reason scriptures say that about aliens is to show that those that follow God are a generous and caring people. It is to show that GOd is a benevolent God.
It does NOT mean that we should be over run with those chosing to break our laws.
As far as the laws of Moses, these were agreed to in advance by the Hebrews. They were not forced on them by God. God has made it clear what his stance is on aliens, Malachi 3: (the last prophet in the OT) makes it clear that the Lord said he will testify against those who oppress and deprive aliens of justice.
I agree that Christians are no longer subject to the law except that which is contained in Acts 15. This new law is written in our hearts by the Holy Spirit and it is founded in love. Jesus gave us the most important commandment and it is to love God with all your heart and all your soul and all your mind. The second he said is like the first and it is to love your neighbor as yourself.
If you can demonstrate how deporting your neighbor demonstrates love for that neighbor then I would love to hear it. In fact, you sound a bit like the Jews who hated the Samaritans.