One fixed theme of the Marvel Universe has been that anti-mutant hysteria from humanity has caused the species known as homo superior,or "mutantkind," to travel into hiding to avoid violence. Serving as a metaphor for marginalized people during the Civil Rights era, and the X-Men struggle against that threat that bigotry poses them and others like them. Believing there must be a better,more peaceful way, Xavier assembles the X-Men to help bridge the divide between humans and mutants.
Source: blastr.com