Unrest in Iran has opened a theological rift within the Shiite sect of Islam, undermining the Iranian regime's founding dogma that is shared by millions of fellow Shiites across the Middle East.

The concept, known as wilayat al-faqih -- literally "guardianship by a jurist" -- holds that, in an Islamic state, a divinely anointed scholar of Islamic law must exercise unquestioned authority over elected officials and the rest of the government.

Iran's...