Ivan was a devout Christian Orthodox believer

Ivan was a devout Christian Orthodox believer, yet in his own special manner. He placed the most emphasis on defending the ruler's divine right to unlimited authority under God. Some researchers attribute Ivan the Terrible's sadistic and brutal actions to 16th-century religious beliefs, such as drowning and burning people alive or torturing captives with boiling or freezing water, which corresponded to the torments of hell. That accorded with Ivan's vision of himself as God's envoy on Earth, with a sacred right and duty to punish. He could also have been influenced by Archangel Michael's model of divine chastisement.

Despite the Church's absolute prohibition on even the fourth marriage, Ivan had seven wives, and he was negotiating to marry Mary Hastings, a distant relative of Queen Elizabeth of England, even while his seventh wife was still alive. Of course, the Church forbade polygamy, but Ivan intended to put his wife away. Ivan boldly intervened in church affairs, deposing the second-oldest hierarch, Novgorod Archbishop Pimen, and ordering his execution and charging him with treason. During the Novgorod Massacre, many monks were tortured to death.

Because he feared the anger of the Ottoman sultan, Ivan was fairly tolerant of Islam, which was widespread in the seized Tatar khanates' domains. His anti-Semitism, however, was so strong that no pragmatic reasons could stop him. For example, following the seizure of Polotsk, all unconverted Jews were drowned, notwithstanding their economic importance to the city.