If you are looking for something that says "Do not mix races" (which obviously you are) you arent going to find it.So many people have said to mix race is sin and state it's in the Bible. I have read the Bible many times and have failed to see anything pertaining to this. Could you share if you think this is true.
However, when translated down to orginial hebrew language you find that God was intent on keeping the races seperated and to keep a pure line, namely for Jesus' lineage and for the other tribes of israel as well. I would imagine he also wanted to firmly establish the different races so that generations to come would continue to have the pleasure of diversity. I personally feel that this would be ideal for all races. Is it a sin? Well a sin seperates us from God, and we can never be at one with God as long as there is sin in our life. So if being a product of a mixed relationship is the product of sin, then that innocent child is born corrupt with out ever having a chance of redemption, because it can not change it mixed status nor repent for the sin of it's parent, hence it would eternally cut off from God (while the parents could repent and receive salvation). This would be absurd. So we must draw the conclusion that God had a special purpose of keeping the races seperated at least for a while, but knowing full well that it would be eventually impossible to maintain. So is it a sin? I dont think so, Jesus died to give everyone a shot at salvation.
But its not ideal either. If we melt all of us together we would get a blur. And how frightening it would be to hear on the news "The last living American Indian Died today" or "The black race to be placed on the endangered species list". To lose all the world's heritages would be a sad day indeed.