We all know that God calls, indeed commands us to love one another. The question is how to go about it. To answer that question I want to share a bit of advice from C. S. Lewis:
The rule for all of us is perfectly simple. Do not waste time bothering whether you ‘love’ your neighbor; act as if you did. As soon as we do this we find one of the great secrets. When you are behaving as if you loved someone, you will presently come to love him. If you injure someone you dislike, you will find yourself disliking him more. If you do him a good turn, you will find yourself disliking him less.
But this has to be done for the right reason. As Lewis goes on to note:
There is, indeed, one exception. If you do him a good turn, not to please God and obey the law of charity [Christian love], but to show him what a fine forgiving chap you are, and to put him in your debt, and then sit down to wait for his ‘gratitude’, you will probably be disappointed. — C. S. Lewis, “Charity,” in Mere Christianity (1952).