Islam strictly prohibits the use of icons, images, or any forms of idol worship. Consequently, depictions of Muhammad are absent. While Catholic churches have fewer icons compared to Orthodox ones, Protestant churches have almost none. In contrast, Orthodox churches are adorned with icons throughout their interiors.

Historical events often provide context for present-day practices, and this is true for the prevalence of icons in Orthodox churches. The rise and spread of Islam in the 6th and 7th centuries sparked debates within Christianity about the use of icons and the depiction of Jesus in human form. Questions arose about the sanctity of relics and whether they violated God’s commandments against idolatry.

This debate had its roots in the 4th and 5th centuries when relics, saints, and icons became increasingly significant to Christian. The practice of “intercessory prayer” grew during this time, where believers would direct their prayers to the Mother of God or saints, believed to have a direct line to Jesus through the Holy Spirit. This led to a belief in the spiritual power of icons and religious relics.

However, a turning point came in the 7th century. The Byzantine Empire, facing defeats from Muslims and internal strife, was further devastated by a volcanic eruption near Santorini in 726. This catastrophe, coupled with previous losses, was seen by many Christians as divine retribution against idolatry.

Emperor Leo III, interpreting these events as signs, unilaterally issued an edict in 730 banning icons. He ordered the replacement of Jesus icons with simple crosses and the removal of all others, viewing them as blasphemous. This decision was met with strong opposition from both church leaders and the public. Patriarch Germanos of Constantinople, fearing that removing icons would validate claims of Christian heresy by Jews and Muslims, sided with those favoring icons and subsequently lost his position.

The reign of Leo III marked a significant shift in the Byzantine Empire’s stance on religious icons. Beyond merely issuing an edict, Leo embarked on a fervent campaign to seize icons, relics, and invaluable church artifacts. This move set him on a collision course with Pope Gregory III. As years passed, opposition to the iconoclasts—those against the use of religious icons—intensified.

However, Leo’s demise in 741 saw his son, Constantine V, ascend the throne. Far from being a moderate, Constantine emerged as one of history’s most zealous iconoclasts. He escalated the campaign against icons, leading to the desecration of churches in Constantinople and even their conversion into secular spaces, including stables.

Under Constantine’s rule, the persecution of Christians, especially priests, became rampant. This era witnessed the martyrdom of iconophile St. Stephen the Younger, who would later be canonized. In a bold move in 754, Constantine convened the Council of Hieria, where he presented his demands for the complete removal of icons from sanctuaries to 340 bishops. The council, in a controversial decision, endorsed his views. They even proclaimed the Council as the “Seventh Ecumenical Council,” aiming for it to hold authority over all Christian denominations. However, its legitimacy was questioned due to the absence of patriarchs from the five primary Christian centers. The “Second Council of Nicaea” in 787 would later overturn its decisions, reaffirming the sanctity of icons.

The subsequent ruler, Leo IV, sought to alleviate the tensions but struggled to find a lasting solution. After his passing, his wife, Empress Irene, a staunch iconophile, took the reins. She convened the Second Council of Nicaea, ensuring the revered return of icons to churches. This council’s decisions marked a significant triumph for the iconophiles, gaining recognition from Pope Hadrian I. However, Protestant reformers and figures like Charlemagne would later challenge its rulings.

The iconophilic stance of Irene and Leo eventually led to their downfall. After a series of upheavals and the rise and fall of emperors, Leo V the Armenian reinstated iconoclasm. Yet, this was short-lived. Empress Theodora, ruling on behalf of her son Michael III, convened the Synod of Constantinople in 843, which once again validated the decisions of the Second Nicene Council. This confirmation was celebrated in Orthodox Christianity as the ‘Victory of Orthodoxy.’

The iconoclastic controversy, spanning over a century, had profound implications. Religiously, it deepened the rift between Christian denominations. Politically, it weakened the Byzantine Empire, empowered the Pope. The Pope’s attempts to dominate other Christian churches further exacerbated the schism, eventually leading to the emergence of Protestantism.

In essence, what began as a seemingly minor dispute transformed Christianity and left an indelible mark on history.