ideocracy
/ˌʌɪdɪˈɒkrəsi/ /ˌɪdɪˈɒkrəsi/noun
Governance of a state according to the principles of a particular (political) ideology; a state or country governed in this way.
Origin
Early 19th century; earliest use found in John Adams (1735–1826), president of the United States of America. From ideo- + -cracy.