Defense against Monothelitism
Sophronius stands among the foremost early opponents of Monoenergism and Monothelitism, the seventh-century teachings that Christ acted by a single divine energy or possessed only a single will. As a monk and later as patriarch he argued that this compromised the full humanity of Christ and amounted to a subtle revival of Monophysitism.
In 633 he traveled to Alexandria and Constantinople seeking to dissuade the patriarchs from the doctrine. Upon his election in 634 he issued a synodical letter, addressed to Pope Honorius I and the Eastern patriarchs, expounding the Orthodox confession of Christ's two natures. He also compiled a large florilegium of patristic texts supporting the doctrine of Christ's two wills. Though much of his polemical writing on the controversy has been lost, his synodical letter survived and was later read at the Third Council of Constantinople, which formally condemned Monothelitism.