Germanus I was an iconodule,[5] and played an important role in defending the use of sacred images during the iconoclastic crisis of his day.

[7] After an apparently successful attempt to enforce the baptism of all Jews and Montanists in the empire (722), Leo III issued a series of edicts against the worship of images (726–729).

[8] A letter by the patriarch Germanus I written before 726 to two Iconoclast bishops says that "now whole towns and multitudes of people are in considerable agitation over this matter", but little evidence is extant as to the growth of the debate.

According to Patricia Karlin-Hayter, what worried Germanus I was that the ban of icons would prove that the Church had been in error for a long time and therefore play into the hands of Jews and Muslims.

[10] Tradition depicts Germanus I as much more determined in his position, even winning a debate on the matter with Constantine, Bishop of Nacoleia, a leading Iconoclast.

[5] His Historia Ecclesiastica was a popular work in Greek and Latin translations for many centuries, and remains often quoted by scholars.

[5] Pope Pius XII included one of his texts in the apostolic constitution proclaiming Mary's assumption into heaven a dogma of the Church.