Saint Leo II, the Pope, known for his commitment to Church unity and sacred music, played a crucial role in approving the Third Council of Constantinople, which condemned the Monothelite heresy. His dedication to liturgical development and care for the poor left a lasting impact on the Church.

After Pope Agatho passed away in January AD 681, Pope Leo II was elected as his successor, the Eightieth Pontiff on August 17, AD682. However, his inauguration was delayed for eighteen months as he awaited the emperor’s approval. During this time, the guardians of the papal throne sent letters to the emperor, informing him of Pope Agatho’s death and Pope Leo II’s election. These letters reached Constantinople on March 10, while the council was still in session. As a result, the Emperor postponed confirming the new pope until the council had officially condemned the proponents of Monothelitism. 

It was Pope Leo who officially approved the acts and decisions of the Third Ecumenical Council of Constantinople, therby officially declaring the heresy of Monothelitism to be a false teaching.

Pope Leo's consecration did not take place until July AD682, when papal legates arrived in Rome with the council's decisions and the emperor's permission to elect a pope. According to the *Liber Pontificalis*, a biography of the early popes, the consecration of Pope Leo II as Bishop of Rome was carried out by Andrea, Bishop of Ostia; Giovanni, Bishop of Porto; and Piacenza, Bishop of Velletri. As a sign of his approval of the election of Pope Leo II, the new head of the Church, and of his warm relations with him, Emperor Constantine IV invited the Pope to send a permanent papal nuncio to Constantinople.

He also granted a remission of taxes levied on the papal patrimony of Sicily and Calabria. He revoked the decree of his predecessor, Emperor Constans II, which had made the Archdiocese of Ravenna independent of Rome in the appointment of its bishops. From then on, all metropolitans of the Archdiocese of Ravenna were consecrated by the popes and received the pallium, the symbol of their pastoral authority.

In response to these approaches of Emperor Constantine IV, Pope Leo II translated the acts and decisions of the Third Council of Constantinople into Latin and published and circulated them among church leaders, diplomats, and political representatives, along with his approval of the council. In recognition of the new status of the Diocese of Ravenna, he exempted the metropolitans from the traditional tax imposed at the time of their consecration. He also exempted the Metropolitan of Ravenna from attending the annual synods that met in Rome.

Before his election, Pope Leo II was a talented singer in the papal choir, which inspired his strong dedication to the advancement of church music. His papacy was also marked by a deep concern for the poor. He passed away on July 3, AD683. His mortal remains were laid to rest in St. Peter’s Basilica.