Gospel songs rang through the sanctuary of a Florida church Sunday afternoon just before Trayvon Martin’s father exhorted the congregation to combat gun violence in black communities or risk losing a generation of young adults. Tracy Martin told a “Black Lives Matter” ceremony at the Praise and Deliverance Church of God By Faith that while police shootings of young black men is a serious issue, it’s not the biggest one in black neighborhoods. A far larger problem, Martin said, is the current generation of African-American children growing up without adult guidance and parental love. While acknowledging America’s intransigent racial divide....