A significant moment in the thawing of relations between the Roman Catholic and Orthodox churches is set to take place today when the pope will hand back the relics of two Byzantine saints looted in the sack of Constantinople. Ecumenical Patriarch Vartholomaios I, Orthodox Christianity’s spiritual leader, arrived in Rome yesterday ahead of today’s ceremony in St Peter’s Basilica, during which Pope John Paul II will return the remains of St Gregory the Theologian and St John Chrysostom. The saints are key Orthodox holy figures and the relics’ return has been sought since 1204, when a western army sacked the Byzantine capital as the Fourth Crusade went awry. Their return is an important reconciliation step between the two churches, which split in 1054. The relics will be welcomed back to Istanbul with a service at the Phanar, and will be buried at the Patriarchal Cathedral on Tuesday.