Last month Nicole C. Mullen sang and signed “I Know that My Redeemer Lives” along with selections from her new album, “War Songs” (based on Psalm 91), at the EPA Christian media convention in Lexington. Afterward, she sat down to talk with me about longevity and the varied faces of faithfulness. Mullen’s grandparents had “sixty-plus-year marriages on both sides of the family,” she said. Her grandfather on her dad’s side “pastored and worked for the phone company for thirty-six years.” Her parents were married for “fifty-four years, five months, and fourteen days” before the death of her father. The latter “also worked for same phone company for thirty-eight years.” And…