In the third chapter of Genesis, after the proverbial “Fall” of humanity, two brothers stand in a field. Cain is a farmer—Abel, a herdsman. Both bring offerings from their labor to God, but Abel brings his first fruits, so God looks on Abel’s offering with delight. In a jealous rage Cain rises up against Abel and kills him. This is the first recorded murder in the Bible. (Genesis 4:8) I will never forget walking onto the National Mall early on the morning of April 11, 2013. As I approached a mass of people and television cameras between the Washington Monument and the Capitol Building I was...