PLAINS OF UR, Iraq — Pope Francis and Iraq’s top Shiite cleric delivered a powerful message of peaceful coexistence Saturday, urging Muslims in the war-weary Arab nation to embrace Iraq’s long-beleaguered Christian minority during a historic meeting in the holy city of Najaf. Grand Ayatollah Ali al-Sistani said religious authorities have a role in protecting Iraq’s Christians, and that Christians should live in peace and enjoy the same rights as other Iraqis.