Roman Catholic Church is seeking to unite all religions for world peace. "Leaders of all faiths should unite in renouncing religious extremism and counter the "barbarity of those who foment hatred and violence," Pope Francis said on Friday at the start of a two-day visit to Cairo. "Let us say once more a firm and clear 'No!' to every form of violence, vengeance and hatred carried out in the name of religion or in the name of God," the pope told a peace conference at Egypt's highest Islamic authority, Al-Azhar. Francis's trip, aimed at improving ties between Muslims and Roman Catholics, comes three weeks after Islamic State suicide bombers killed at least 45 people in two Egyptian churches.