What factor makes a system of government a theocracy and not a republic?

A theocracy is characterized by the belief that religious leaders or institutions hold ultimate authority, often governing based on religious laws and principles. In contrast, a republic is defined by elected representatives and a constitution that upholds individual rights and secular governance. The key distinction lies in the source of authority: theocracy derives its legitimacy from divine or religious mandates, while a republic is rooted in the will of the people and democratic principles.