Several groups have held rallies in Athens and held all-night vigils in monasteries to pray against the visit. The tension includes a debate over whether it would be offensive for the pope to kiss Greek soil upon his arrival. Catholic officials in Greece proposed earlier this week that the pontiff break a 22-year tradition and not kiss Greek soil. They worried that some Greeks would construe the gesture as a sign of Vatican claims on mostly-Orthodox Greece and said Wednesday that he would only receive olive branches and flowers at the Athens airport. But Vatican officials on Thursday said the traditional ground-kissing would indeed be part of the arrival.
Monasteries plan to ring their bells in mourning during the visit.
The Orthodox Church is one of the three major branches of Christianity, alongside Catholicism and Protestantism. The churches differ over the authority of the pope and other issues. Scholars say the protesters are expressing concerns shared, at least in part, by people concerned about the encroachments of European politics and Western religion. After Athens, the pope will go to Syria and Malta. In June, he plans to visit Ukraine, where tensions between Catholics and Orthodox are even stronger.