The ego survives by drawing lines, marking who belongs and who is foreign, who is one of us and who is other. Yet the sense that anyone is truly a stranger arises only in the mind. The same consciousness that looks out through your eyes looks out through theirs.
To love the stranger as yourself is not a moral effort you impose on yourself. It is the natural recognition that they are yourself, the same Being wearing another form. When you have known the pain of being treated as an outsider, you can feel that shared aliveness directly, and the distance your mind invented between you and them quietly falls away.