The word of God commands us to love God and our neighbor (Matthew 22:36-40).
Why?
We are originally created for love. All our body organs work perfectly in love. We enjoy life when we live in love. Not loving God and others is the shortest and easiest way to make our life miserable. And guess what? Our vital organs, primarily our hearts and kidneys, work efficiently when we love God and others. Our body parts are perfectly compatible with love, and incompatible with hate.