Have you ever traveled to other countries and be so mistreated? Or discriminated? Or robbed?
9 Also thou shalt not oppress a stranger: for ye know the heart of a stranger, seeing ye were strangers in the land of Egypt. – (Laws about Social Justice – Exodus 23:1-9 KJV)
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God sees all that. There is a command about that. In the U.S. there are anti-discrimination laws. There is that, because it is apparent and abundant – getting discriminated hurts, for strangers, for foreigners. But it is not exclusive to any one country. Discrimination has happened even long before.
God commands it. Because everyone is created in His image.