Metta is the act of extending our love, kindness and friendship equally towards all beings, proving that love is more powerful than any negative force. Rather than trying to deal with negativity, we cultivate the opposite; seeing and knowing pain, we bring loving kindness. Then amazing change is possible.
Religious intolerance arose with presumptions of certainty: the sureness that my sect possesses certified knowledge means that I cannot endure your sect's evident error. If it had always been accepted that belief does not rise to the level of knowledge, religious intolerance might not have marred our histories.