Democrats vs Republicans, Conservative vs Liberals, Muslims vs Christians are all divisions that favor capitalism. Why? Because when people are divided they dislike each other and don't feel bad when they get ahead at the expense of their rivals.

In socialism or communism one necessary condition is people understanding each other, caring about each other and feeling unity about each other. In this environment more things are done for the benefit of the community.

The portion in bold is what J.S Mill writes.