It must really please our heavenly Father when He sees His children living in unity and harmony. In his word God has given some guidelines to help us. In Philippians 2:1-4 He tells us to be like minded, to have the same love, to be in one accord and to do nothing through selfishness or conceit. It also tells us to not lookout for our interest only, but the interest of others.
Can you imagine what a great place it would be to live if just those who really are Christians lived totally by these rules?
Since the Psalmist used the word brethren, it seems to indicate he was talking about people who loved and served the living God.
In Colossians 3:14, The apostle Paul tells us to put on love, which is the perfect bond of unity. This would indicate to us then, that love is the answer to all of our problems, whether it is in our marriages, our families, our churchs, our jobs or our neighborhoods.
Every thing we do should be bathed in love.