Divine right made kings answerable to God alone, and it was newer than it sounds
The idea that a monarch answers only to heaven feels ancient, yet in Europe it hardened only after the Reformation. Medieval kings could be excommunicated and even deposed by the Church. Divine right removed that referee, leaving no earthly power, not the Pope and not parliament, entitled to judge the crown.
In the medieval order known as the Res publica Christiana, a king was legitimate only while he governed within a ladder of laws that Thomas Aquinas described: eternal law, the divine plan; natural law, which reason can grasp; and human law, shaped by local custom. The Church decided whether a ruler was keeping to that order, which is why excommunication terrified monarchs. Power was also shared with nobles and parliaments such as the Iberian Cortes, and Aquinas himself favoured a monarchy restrained by a strong parliament.
The Reformation and then the Thirty Years' War knocked the Church off its perch as final political arbiter. In its place grew the doctrine that a king holds authority straight from God, so resisting or restricting him is not merely rebellion but something close to sacrilege. It is linked above all with Henry VIII and his Acts of Supremacy, James VI and I, and Louis XIV, and it underpinned the Age of Absolutism, roughly 1610 to 1789. Strictly, it said who could judge a king, not that his power had no limits; the formula "by the Grace of God", or Dei Gratia, on royal titles expresses it.
Other traditions reached similar ideas by different roads. The Mahabharata describes people before kings devouring one another like big fish eating small ones until they begged the creator for a ruler, and treats the king as an embodiment of Indra. The Markandeya Purana asks a king to act like the Sun, the Moon, the Wind, Indra and Yama. Iran had khvarenah, a divine glory without which no king could reign; one story has it leaving the Parthian Artabanus V in the shape of a ram to follow Ardashir I.
Jewish thought argued the point for centuries. Deuteronomy allows Israel to set a king over itself, and rabbis debated whether choosing one undercut divine right until Maimonides concluded that appointing a king was one of three commandments. A blessing is still said on seeing a monarch.
Source: Divine right of kings
