In ancient times, divine kingship was a fundamental and nearly universal religious and political reality. The gods had created the cosmos, which required their constant sustaining attention. Rain, fertility, storms and earthquakes were all directly attributed to them. The cosmos was ordered by divinely established natural law, while mankind was ordered by divinely established social law.
Both social laws and the political authority to establish and sustain those laws came from the gods, like everything else in the cosmos. Both the institution of kingship and individual kings had been ordained by the gods. The divine authorization of the king was most manifest when the gods granted victory to him in battle.
While nearly all ancient civilizations agreed that both kingship and individual kings derived both their existence and their authority from the gods, the exact nature of the relationship between gods and kings could vary widely.
Often, as in the case of the Egyptian pharaoh, the king was considered an incarnate god.
Likewise, a king could be the "son of a god" in a most literal sense. Alexander the Great, for example, was told by the Egyptian oracle at Siwa that he was the son of Zeus/Amun. Chinese emperors were the "son of heaven/god" and ruled by the "mandate/authorization of heaven/god."
Ancient rulers frequently claimed descent from the gods; Julius Caesar dedicated a temple in the Roman Forum to his divine ancestor "Venus Genetrix/mother." Kings of Europe often claimed to have been chosen by God, with their coronation by Christian priests reflecting the "divine right of kings."
Divine kingship was also found among ancient Israelites. Psalm 2, for example, extols the king as the son of God. "Yet have I set my king upon my holy hill of Zion (the temple mount). I will declare the decree: the LORD hath said unto me, 'Thou art my Son; this day have I begotten thee. Ask of me, and I shall give thee the heathen for thine inheritance, and the uttermost parts of the earth for thy possession'" (Psalm 2:6-7). This concept of divine kingship became intimately bound up in Jewish messianic expectations.
There were, of course, exceptions to this phenomenon. Sometimes, the rejection of tyrannical kings culminated in the rejection of kingship altogether. This was especially the case in early Rome and Athens, the fountainheads of modern democracy. Yet, remarkably, these proto-democracies proved unstable; both ultimately reverted back to forms of divine kingship, with Alexander and the divine kings of the Hellenistic age, and the divine emperors of imperial Rome.
Though once nearly universal, divine kingship has faded in the past two centuries. One of the fundamental characteristics of the modern world has been the transference of the ultimate source and foundation of political authority from God to the people.
Ironically, today both democracy and communism claim their authority to rule in the name of the people/proletariat. This is largely because, rather than being shepherds for their people, kings all too often proved to be corrupt and decadent tyrants who regularly oppressed their subjects. Their claims to divine investiture thus became blasphemous parodies.
Today, we find few monarchies in the world where the rulers' authority is fundamentally religious. With some notable exceptions such as the Saudis, most surviving monarchies today rule merely as cultural figureheads.
In the world today, the "will of the people" has thus largely replaced the "will of God" as the source of legal and political authority.
Nonetheless, a few vestiges of ancient divine kingship survived into the 20th century. Hirohito, the emperor of Japan during World War II, was believed by the Japanese to be a god incarnate ("arahitogami") and a descendant of the sun-goddess Amaterasu. He was forced to publicly renounce his claim of divinity only in 1946, according to the surrender terms of World War II.
Until nine years ago, when he was overthrown by a democratic revolution, Gyanendra Bir Bikram Shah Dev, the king of Nepal, was considered an incarnation of the Hindu god Vishnu.
Perhaps the last surviving god-king in the world is Tenzin Gyatso, the current Dalai Lama ("world teacher") of Tibet, who is venerated by his people as the 14th divine reincarnation of the divine Avalokiteshvara Buddha. However, exiled in India since the Chinese communist conquest of Tibet in 1959, he is a god-king without a country. And, in recent years, he has grappled with the possibility that he will be the last Dalai Lama and, hence, the last god-king.