Yoav Ben-Tsur officially became a lawmaker Monday, following Shas MK Ariel Attias' resignation last week. 'To be an MK is a holy mission and a heavy responsibility,' he said in his first speech to the plenum, adding that he was a messenger for deceased Shas spiritual leader Rabbi Ovadia Yosef in all his public roles. Ben-Tsur, 56, was director-general of Shas' chain of schools from 2007 to 2013. He is a rabbi and has a Masters degree in Business and Public Administration.