BY THE GRACE OF GOD

'By the Grace of God', as well as the various equivalent phrases in other languages thus rendered in English,
is not a title in its own right, but a common introductory part of the full styles of many Monarchs, preceding the actual princely styles in chief of the specific realm(s) and/or other principalities (King of X, Duke of Y, etc.).
For example, according to the "Royal Proclamation reciting the altered Style and Titles of the Crown" of May 29 1953, Elizabeth II's full title is "Elizabeth II, by the Grace of God, of the United Kingdom of Great Britain and Northern Ireland and of Her other Realms and Territories Queen, Head of the Commonwealth, Defender of the Faith"; in the various other Commonwealth Realms, variations are used, specifying the realm in question and varying some of the other elements of the title.

Contents

History and Rationale

In modern languages

Compound formulas

Sources and references

History and Rationale

Originally, it had a literal meaning: the divine will was invoked -notably by Christian Monarchs -- as legitimation (the only one above every earthly power) for the Absolutist authority the Monarch aimed at. This is also known as the divine right of kings, that is, the endorsement of God to the monarch's reign.
In the Behistun Inscription high over the road connecting Babylon and Ecbatana, the capitals of Babylonia and Media, the Achaemenid Persian King of Kings Darius I the Great had inscribed, in the Old Persian, Akkadian and Elamite languages:
:"King Darius says: By the grace of Ahura Mazda am I king; Ahura Mazda has granted me the kingdom."
Then he had the ledge chipped away that had supported the stonemasons, so passing travellers could read the inscription.
As in Antiquity it was quite common for pagan deities to be equated with each other and/or adopted by conquerors in their pantheon, the fact that 'god' was often another deity was no objection for passing on evotional styles or even legitimation. Thus "King by the grace of God" passed from the Persian monarchy to the heirs of Alexander, and was taken up by the later Roman emperors, who ultimately christianized it when adopting Christianity as the new official religion. And so it passed into Europe.
While the Christian Roman emperors during the late Dominate, especially in the east (as continued in Byzantium after the fall of Rome), came remarkably close to acting out the role of God's voice on earth, centralizing all power in their hands, e.g. reducing the Patriarch of Constantinople to their "(State) Minister of the Cult" and proclaiming their "universal" authority (in the Oriental tradition as in Persia, but also in the original Muslim Caliphate), for most dynasties it would rather prove to be a never-ending battle up the hills of political resistance, both from rival power poles within their state (nobility, clergy, people; even within a dynasty) and from foreign powers claiming independence or even hegemony, usually constraining them in constitutional limitations (not necessarily written statutes, more often a matter of customary law and established privileges).
By custom, it is restricted to sovereign rulers; in the feudal logic a vassal could not use the phrase, because he held his fief not by the grace of God, but by grant of a superior noble, (in)directly from the crown; yet this didn't stop kings to continue using it even when some of them did homage to the pope (as viceregent of God).
While the "incantation" of divine Grace became a prestigious style figure that few Christian monarchies could resist, it is not a literal carte-blanche from Heaven, but rather a consecration of the "sacred" mystique of the crown. Some of that survives even in modern constitutional monarchies where all power has been transferred to elected (party) politicians. In modern, especially recently (re-)founded monarchies, more realistic power reports (often crucially a voice in the succession and the purse strings) do in time find expression, sometimes even in abandoning "By the Grace of God", or rather, especially earlier, in the intercalation of compensatory phrases, such as "and the will of the people", and/or replacing the genitive "sovereign of X-place" by "sovereign of the X-inhabitants", quite meaningful where linked to the Enlightenment-notion of the "social contract", which means the nominal 'sovereign' is in fact potentially subject to national approval, without which a revolution can be legitimate.
Today, even though all western monarchies are constitutional, all political power having passed to the people (by referendum or, generally, elections), the now hollow traditional phrase "by the grace of God" is still included in the full titles and styles of the monarchs of Denmark, Liechtenstein, the Netherlands and the United Kingdom, but not in that of Belgium, Luxembourg, Monaco, Norway and Sweden. Like the use of the term "subject" for the citizens of a monarchy, "By the Grace of God" is a protocolary form that has survived the emancipation of the electorate from its once absolute rulers, which now only reign in name.
Spain's Spanish Constitution of 1978, in article 56, §2, states that the title of the King of Spain is simply "King of Spain" (''Rey de España''), but that he also possesses the traditional titles of the Spanish Crown (''podrá utilizar los demás que correspondan a la Corona''). As a result, the King of Spain continues to be King "by the grace of God".
Parallels exist in other civilizations, e.g. Mandate of Heaven of the Chinese empire, where for centuries the official decrees by the Emperors of China invariably began with the phrase _(pinyin)"Fèng Tiān chéng yùn, Huángdì zhào yuē" (奉天承運 皇帝詔曰) which is translated as "By the Grace of Heaven, the Emperor decrees".

In modern languages

:This list, possibly incomplete, is limited to phrases that are/were formally used by monarchies of the (mainly western/Christian) tradition in their official styles.
Germanic languages:

★ ''By the Grace of God'' (English)

★ ''By die Grasie Gods'' (Afrikaans)

★ ''Af Guds nåde'' (Danish), pre-1948 spelling: ''Af Guds Naade'')

★ ''Bij de Gratie Gods'' (Dutch)

★ ''Von Gottes Gnaden'' (German)

★ ''Af Guðs náð'' (Icelandic)

★ ''Av Guds nåde'' (Norwegian)

★ ''Av Guds nåde'' (Swedish)
Romance languages:

★ ''Dei Gratia'' (Latin), often abbreviated as D.G.; ''these Latin forms are often used besides the national language(s), or even in stead''

★ ''Per la gràcia de Déu'' (Catalan)

★ ''Par la Grâce de Dieu'' (French)

★ ''Per la grazia di Dio'' (Italian)

★ ''Por graça de Deus'' or ''Pela graça de Deus'' (Portuguese)

★ ''Por la Gracia de Dios'' (Spanish; in Spain dropped since 1978, replaced by ''Rey Constitucional'' de España, etc.)

★ ''Din Mila lui Dumnezeu'' (Romanian)
Slavonic and Baltic languages:

★ ''Po bozija milost'' (Bulgarian)

★ ''Milošću Božjom'' or ''Božjom milošću'' (Croatian)

★ ''ar Dieva žēlastību'' (Latvian)

★ ''Dievo malone'' (Lithuanian)

★ ''Z Bożej łaski'' (Polish)

★ ''Bozhiyeyu milostiyu'' or ''Bozhiyeyu pospeshestvuyushcheyu milostiyu'' (Russian)

★ ''Po milosti Božjoj'' (Serbian)
Other languages:

★ ''Isten kegyelméből'' (Hungarian)

★ ''Ελέω Θεού'' (''Eleō Theou'') (Greek)

★ ''By the will of our Lord'' is an equivalent formula in Orthodox Georgia

★ '「奉天承運」' ''By the Mandate of Heaven and Grace of Divinity'' is a phrase used by Chinese monarchies in the times of Imperial China.

Compound formulas

In some cases, the formula was combined with a reference to another legitimation, especially such democratic notions as the social contract, e.g.

★ Oliver Cromwell was Lord Protector ''by the Grace of God, and the Republic'', denoting that he was chosen by God to rule but he was put there by the people of the 'Commonwealth' (British republic).

★ 'By the Grace of God and the Will of People' in Kingdom of Serbia and Kingdom of Yugoslavia.

★ Sovereigns of the Kingdom of Hawai'i were styled "By the Grace of God and under the Constitution of the Hawaiian Islands, King (or Queen)"

Sources and references

★ The Behistun inscription.

★ RoyalArk- here Georgia

★ WorldStatesmen- see each present country