Images of Christ are idols

Doctrine · On images and the saints · 754–787

To depict Christ is either to circumscribe his divinity or to divide his person, and the images set up in churches are idols.

The horos of Hieria, which reasoned from Chalcedon: the two natures cannot be painted, since one is uncircumscribable and the other cannot be shown alone. Nicaea II answered on the same ground and reached the opposite conclusion.

Held it

726 — Leo III the Syrian (Holds). Orders the images removed, beginning the first iconoclasm. The Orthodox Church in the Byzantine Empire · Hussey, part 1, on the iconoclast controversy
754 — The Council of Hieria (Defines). Declares the images unlawful and orders them taken down, reasoning that Christ cannot be circumscribed. The Seven Ecumenical Councils (NPNF series 2 vol. 14) · Nicaea II (787), the refutation of the Definition of Hieria
754 — The Definition (Horos) of Hieria (Formulates). The text, which survives because Nicaea II quotes it in order to answer it. The Seven Ecumenical Councils (NPNF series 2 vol. 14) · Nicaea II (787), the refutation of the Definition of Hieria

Refused it

787 — The Second Council of Nicaea (Anathematizes). Answers the Definition of Hieria clause by clause and anathematizes it. The Seven Ecumenical Councils (NPNF series 2 vol. 14) · Nicaea II (787), the refutation of the Definition of Hieria

In the disputes

Iconoclasm Whether Christ may be depicted, argued from Chalcedon by both sides: Hieria held that the two natures cannot be painted, since one cannot be circumscribed and the other cannot be shown alone; Nicaea II answered on the same ground and reached the opposite conclusion.

First stated in this form after The Seven Ecumenical Councils (NPNF series 2 vol. 14) · Nicaea II (787), the refutation of the Definition of Hieria.