press photo by dana grubbIrish tenor Emmet Cahill performed at First Presbyterian Church of Bethlehem, regaling the nearly 300 in attendance March 20 with a selection of spiritual, popular and traditional Irish songs. Cahill, 26, who has performed with Celtic Thunder since 2011, has embarked on a solo career. His newest CD, “Emmet Cahill's Ireland,” debuted at No. 1 on Billboard's World Music