Racism can be based on religion, language, or ethnic group. It is, however, wrong under any circumstances. Culture changes in two broad ways. People find or adapt new methods of doing the same thing. This is cultural change.
People find new reasons to do things, or completely new things to do.
For example, when a new religion is introduced to an area, there will new religious practices to be undertaken. When the Romans conquered an area, they always abolished human sacrifice. Christianity once required its members to abstain from meat every Friday. When a country adopts a democratic government, people accused of crimes must be publicly tried, and other rights are introduced. These are examples of social change.