From Dictionary.com
rac⋅ism
   /ˈreɪsɪzəm/ Show Spelled Pronunciation [rey-siz-uhm] Show IPA
?noun
1. a belief or doctrine that inherent differences among the various human races determine cultural or individual achievement, usually involving the idea that one's own race is superior and has the right to rule others.
2. a policy, system of government, etc., based upon or fostering such a doctrine; discrimination.
3. hatred or intolerance of another race or other races.
Because you are white and you violently massacre a person who is black does not make you inherently a racist. Saying it does makes one a racist because they have demonstrated a policy based on race. Like a lot of criminal law, intent is the name of the game. Its the same distinctions that mark the differences between manslaughter and Murder 1 (going on the US criminal justice system which is all I am familiar with). Manslaughter is you kill someone unintentionally and Murder in the first degree implies you kill someone with forethought and malicious misgivings.
If you single out and kill people because they are black, you are a racist. If you kill someone who happens to be black, but kill them because they are in a rival gang, your okay

.
I have said this in other threads, but to label games like Saint's Row 2 or RE5 racist is, in itself, a racist act. By saying that people of African decent should be treated, as a race, differently because of their history is creating a policy based on race and is, therefor, racist.
[/same old rant]