What were Leo III’s reasons for opposing religious icons?

The origins of Leo III’s opposition to religious icons, known as Iconoclasm, remain somewhat obscure and are a subject of historical debate. However, several factors are identified as contributing to his stance:1

• Personal Religious Conviction: Leo III was a deeply religious man who became genuinely convinced that the veneration of religious pictures and relics in worship services was sacrilegious.1
• Influence of Regional Opinions: He was influenced by the iconoclastic views held by certain bishops in western Asia Minor.1
• Potential External Influences: While critics often charged that his upbringing in northern Syria exposed him to Islamic influences that shaped his views, this remains uncertain.1
• Imperial Duty: Leo III possessed a profound belief in his duty as emperor to implement his religious opinions as he understood them, viewing it as his responsibility to guide the spiritual life of the empire.1

Ultimately, in 730, he formalized this belief by declaring Iconoclasm the official policy of the empire, mandating the removal and destruction of sacred images.1