The word "racism" cannot be found in the KJV translation of Scripture. The modern meaning of the word is founded on the concept that there are distinct races of man. Each of these, it is believed, has their own unique characteristics based on heredity. Those who believe in racism arbitrarily define some of these characteristics (skin color, etc.) as being more advantageous and superior than others.
Racism feeds into man's focus on himself and his innate desire to compete. It can easily lead to thinking that certain groups are better than others are and that those considered superior should exploit and dominate those considered inferior.
The concepts and ideas that underpin this belief system have been around for a very long time. The word itself, however, is of a relatively recent origin. Few would be surprised to know that the word began to be used in the early to mid-1930s in Germany. It was a term used in Nazi theories in the context of their believed superiority over others.
Let us apply the principle of Jesus' "golden rule" (Matthew 7:12) to racism. Would you like someone to reject, and even hate, you because of your skin color or ethnic origin (which you had no choice over)? Wouldn't you want a chance to show them that you were a decent person, albeit flawed like everyone else, but still worthy of acceptance and being treated fairly?
We humans have far more in common with each other than we might think, as God made us all of one blood (Acts 17:26). We all eat, sleep, drink, go to the bathroom, and share numerous other characteristics.
Whatever differences we have compared to others (God would consider it variety) does not make us any less human than anyone else and leaves no room for racism.
Variety and More Variety
God created a large variety of life on earth and gave such life, like ourselves, the ability to express even more variety within the confines of His standards. We humans are as diverse as we are because our Creator wanted it that way. Believing in racism, that certain groups with some common characteristics are not only inherently superior but also have the right to dominate others, is a direct criticism of the Eternal and an affront to his holy and righteous character of perfect love.
In conclusion, based on the Bible, Christians should not indulge themselves in racism. The superficial characteristics we might deem important in this life do not, and should not, matter to those with God's spirit in them (1Corinthians 12:12 - 13). After all, the physical traits we see in the world will someday disappear after we are resurrected and given a new spirit body (see 1Corinthians 15:35 - 49) based on the one God possess.