The Sasanian kings claimed divine authority as agents of god.

Evidence

For the Sasanian kings were not just secular rulers: they were agents of god, and Shapur’s full titles emphasize his religious role: ‘the good worshipper of god, Shapur, the king of Iran and non-Iran, of the divine race of God, the King of Kings’. — Neil MacGregor, A History of the World in 100 Objects, 687

Categorization

• corroborated: 2 independent passages support this claim — Neil MacGregor, A History of the World in 100 Objects, 687
• XREF: connects to: Some insurgent leaders claimed royal mandate and divine communication.