Non-believers who have never read the Bible seem to have a habit of making long lists of what kind of horrible things it contains. One thing that almost always makes the list is racism. But what does the Bible actually say about racism?
And Mariam and Aaron spoke against Moses on account of the Ethiopian woman whom Moses had taken, because he had taken an Ethiopian woman. And they said, "The Lord has not spoken only to Moses, has he? Did he not also speak to us?" And the Lord listened. And the man Moses was very meek, more than all the people who were upon the earth. And the Lord said at once to Moses and Mariam and Aaron, "Come out, you three, to the tent of witness." And the three came out to the tent of witness. And the Lord descended in a pillar of cloud and stood at the door of the tent of witness. And Aaron and Mariam were called, and they both came out. And he said to them, "Hear my words: If there is a prophet of you for the Lord, in a vision I will be known to him, and in sleep I will speak to him. Not so my attendant Moses; in my whole house he is faithful. Mouth to mouth I will speak to him, in visible form and not through riddles. And he has seen the glory of the Lord. And why were you not afraid to speak against my attendant Moses?" And the anger of the Lord's wrath was against them, and he departed. And the cloud withdrew from the tent, and behold, Mariam was leprous like snow, and Aaron looked upon Mariam, and look, she was leprous. And Aaron said to Moses, "I beg you, Sir, do not lay extra sin upon us, because we were ignorant in that we sinned. Do not let her be like unto death, like a miscarriage coming out of a mother's womb, and it devours half her flesh." And Moses cried out to the Lord, saying, "O God, I beg you, heal her!" And the Lord said to Moses, "If her father when spitting had spat in her face, would she not be put to shame for seven days? Let her be separated for seven days outside the camp, and afterwards she shall enter." And Mariam was kept apart outside the camp for seven days, and the people did not set out until Mariam was cleansed. [Numbers 12]
In other words, marrying a person of a different colour or race is perfectly fine, speaking against those who do is ignorance and sin, and racists are deserving of leprosy and exclusion from the rest of society. Not sure it could be much clearer than that.