Principal among the ecclesiastical issues that separate the two churches is the meaning of papal primacy within any future unified church. The Orthodox insist that it should be a "primacy of honor", as in the ancient church, and not a "primacy of authority", whereas the Catholics see the pontiff's role as required for its exercise power and authority the exact form of which is open to discussion with other Christians. According to Orthodox belief, the test of catholicity is adherence to the authority of "Scripture" and then by the "Holy Tradition" of the church. It is not defined by adherence to any particular see. It is the position of the Orthodox Church that it has never accepted the pope as "de jure" leader of the entire church.