Race, is an social construct that humans used to group other individuals based on their physical features like skin colour and hair texture and etc. However, racism is the belief that one's race is better or more superior than another race. So, racism can take on several forms, such as discrimination, stereotyping and etc.
Racism is a sin, which must be recognized and then dealt with. So, yes atonement, is absolutely necessary. First step, is humility. Racism is deeply rooted in the spirit of pride, hence if its to be atoned, one must recognized their view and treatment of the others as a wrong action and apologize for that behaviour. Then the second and final step is establishment. Establishing an relationship with the other person of a difference race and then RESPECTING them as your fellow human being is key. Furthermore, you help that individual to remove any obstacles that had been set in place to undermine them from reaching their full human potential.
At the end, everyone benefits. For one, God's love can start to grow and manifest in the relationship. Also, there is a sense of peace. Lastly, each person ends up enriching each other. Having a richer life experience compared to when living in racism.