Despite efforts on the part of Catholic Popes and Orthodox Patriarchs to heal the schism, only limited progress towards reconciliation has been made over the last half-century. One stumbling block is the fact that the Orthodox and the Catholics have different perceptions of the nature of the divide. The official Catholic teaching is that the Orthodox are schismatic, meaning that there is nothing heretical about their theology, only their unwillingness to accept the supremacy of the Pope which is presented in Catholic teaching as chiefly an ecclesiological issue, not so much a theological one. The Orthodox object to the Catholic doctrines of Purgatory, Substitutionary atonement, the Immaculate Conception, and papal supremacy, among others, as heretical doctrines. With respect to Primacy of the Pope, the two churches agree that the Pope, as Bishop of Rome, has primacy although they continue to have different interpretations of what that primacy entails.