If the place is Constantinople then the answer is: because he wouldn't recognize his authority as a pope.
Because he wouldn't recognize his authority as a pope.
The Eastern Orthodox Church.
Pope Benedict IX
Pope Leo IX excommunicated the Bishop of Constantinople, Michael I Cerularius, primarily due to disputes over church authority and doctrinal differences between the Western and Eastern Christian traditions. The tensions escalated over issues such as the use of unleavened bread in the Eucharist and the authority of the Pope versus the Patriarch of Constantinople. This excommunication in 1054 was a significant moment in the growing divide between the Roman Catholic Church and the Eastern Orthodox Church, contributing to the Great Schism.
The last to be elected when not yet a bishop was Pope Gregory XVI in 1831, and the last to be elected when not even a priest was Pope Leo X in 1513.
The debate that prompted Pope Gregory II to excommunicate Byzantine Emperor Leo III revolved around the issue of iconoclasm, specifically Leo's edict against the veneration of icons and his efforts to remove religious images from churches. The pope viewed this as a direct challenge to the authority of the Church and a threat to traditional Christian practices. Gregory II's excommunication of Leo was a significant moment in the growing divide between the Eastern Orthodox Church and the Roman Catholic Church, highlighting the tensions over religious authority and the role of images in worship.
I think pope Leo I
because he decided to start a fake religion
Pope Leo XIII was the pope in 1896. He was pope from 1878 to 1903.
Pope Leo became the Pope in 1513, his name also changed from Giovanni di Lorenzo de' Medici to Pope Leo.
Another answer from our community:because despite leo's arguments many church leaders in esatern europe most notably the byzantine patriarch michael cerularius refused to recognize the supremacy of the pope
Pope Leo I, who is also known as St. Leo the Great by Catholics, was Bishop of Rome and thus Pope from 440 to 461. Leo strengthened the central authority of the Bishop of Rome in the early church, and is famous for going out to meet Attila the Hun to convince him not to invade and plunder Rome. In 451, he sent a letter, known as the Tome, to the Council of Chalcedon. When the letter was read to the bishops in attendance, they are recorded as proclaiming "Peter has spoken through Leo". This was perhaps the first public expression of what is now called the "Petrine authority" of the pope as successor of St. Peter.