Allah as a lunar deity

The postulation that Allah (the name of God in Islam) historically originates as a moon god (who was worshipped in pre-Islamic Arabia) originates in early 20th-century scholarship.
The word 'Allah' is a common Arabic term for the supreme God (as opposed to 'ilah', any god), and is widely used by Arabic-speaking Christians and Jews and also found in Arabic translations of the Bible.
The idea was first proposed by archeologist Hugo Winckler in 1901, when he identified the pre-Islamic Allah with another pre-Islamic Arabian deity known as Hubal, which he referred to as a lunar deity. More recent scholars have rejected this view, partly because it is speculation but also because they believe a Nabataean origin would have made the context of South Arabian beliefs irrelevant.
It was widely propagated in the United States in the 1990s, first via the publication of Robert Morey's pamphlet "The Moon-god Allah: In Archeology of the Middle East" (1994), eventually followed by his book "The Islamic Invasion: Confronting the World's Fastest-Growing Religion" (2001). 
Morey's ideas were popularised by cartoonist and publisher Jack Chick, who drew a fictionalised cartoon story entitled "Allah Had No Son" in 1994.
Morey argues that "Allah" was the name of a moon goddess in pre-Islamic Arabic mythology, the implication being that "Allah" as the term for God in Islam implies that Muslims worship a different deity than the Judeo-Christian one. The use of a lunar calendar and the prevalence of crescent moon imagery in Islam is said by some to be the origin of this hypothesis. Joseph Lumbard, a professor of classical Islam, has stated that the idea is "not only an insult to Muslims but also an insult to Arab Christians who use the name 'Allah' for God."
The Quran itself forbids moon worship in 
Evidence adduced.
Etymology.
The word "Allah" predates Islam. As Arthur Jeffrey states:
 The 19th-century scholar Julius Wellhausen also viewed the concept of "Allah" ("al-ilah", the god)" to be "a form of abstraction" originating from Mecca's local gods.
Hebrew words for God include El and Eloah. SOAS Professor Alfred Guillaume notes that the term "al-ilah" (the god) ultimately derives from the Semitic root used as a generic term for divinity.
Guillaume notes that some scholars have argued that the epithet "the god" was first used as a title of a moon god, but this is purely "antiquarian" in the same sense as the origins of the English word "god":
The word "Allah" is used by Arabic-speaking Christians and Jews in Arabia It was also used by pre-Muslim Arab monotheists known as hanifs.
Lunar calendar.
The moon plays a significant role in Islam because of the use of a lunar Islamic calendar to determine the date of Ramadan. The crescent moon, known as Hilal, defines the start and end of Islamic months as it did for the Babylonian calendar. The need to determine the precise time of the appearance of the hilal was one of the inducements for Muslim scholars to study astronomy. The Quran emphasises that the moon is a sign of God, not itself a god.
Crescent moon imagery.
The crescent moon symbol used as a form of blazon is not a feature of early Islam, as would be expected if it were linked to Pre-Islamic pagan roots. The use of the crescent symbol on Muslim flags originates during the later Middle Ages. 14th-century Muslim flags with an upward-pointing crescent in a monocolor field included the flags of Gabes, Tlemcen (Tilimsi), Damas and Lucania, Cairo, Mahdia, Tunis and Buda.
Franz Babinger alludes to the possibility that the crescent was adopted from the Eastern Romans, noting that the crescent alone has a much older tradition also with Turkic tribes in the interior of Asia. Parsons considers this unlikely, as the star and crescent was not a widespread motif in the Eastern Roman Empire at the time of the Ottoman conquest.
Turkish historians tend to stress the antiquity of the crescent (not star-and-crescent) symbol among the early Turkic states in Asia. In Turkish tradition, there is an Ottoman legend of a dream of the eponymous founder of the Ottoman house, Osman I, in which he is reported to have seen a moon rising from the breast of a Muslim judge whose daughter he sought to marry. "When full, it descended into his own breast. Then from his loins there sprang a tree, which as it grew came to cover the whole world with the shadow of its green and beautiful branches." Beneath it Osman saw the world spread out before him, surmounted by the crescent.
Islamic flags containing the calligraphy of the Quran were commonly used by the Mughal Emperor Akbar, it was the Mughal Emperor Shah Jahan, who is known to have inlaid the Crescent and Star symbol upon his personal shield, his son Aurangzeb is also known to have used similar shields and flags containing an upward Crescent and Star symbol. Various Nawabs, such as the Nawab of the Carnatic, also used the Crescent and Star symbols.
Arabian idol Hubal.
Before Islam, the Kaaba contained a statue representing the god Hubal, which was thought by the locals to have powers of divination. The claim draws on historical secular scholarship about the origins of the Islamic view of Allah and the polytheism of pre-Islamic Arabia, which date back to the nineteenth century. These concern the evolution and etymology of "Allah" and the mythological identity of Hubal.
Scholarly views.
On the basis that the Kaaba was Allah's house, but the most important idol within it was that of Hubal, Julius Wellhausen considered Hubal to be an ancient name for Allah.
The claim that Hubal is a moon god derives from the early twentieth century German scholar Hugo Winckler. David Leeming describes him as a warrior and rain god, as does Mircea Eliade.
More recent authors emphasise the Nabataean origins of Hubal as a figure imported "into" the shrine, which may have already been associated with Allah. Patricia Crone argues that "If Hubal and Allah had been one and the same deity, Hubal ought to have survived as an epithet of Allah, which he did not. And moreover there would not have been traditions in which people are asked to renounce the one for the other."
No iconic representation or idol of Allah is known to have existed.
Christian proponents.
Robert Morey's book "The Moon-god Allah in the Archeology of the Middle East" claims that Al-‘Uzzá is identical in origin to Hubal, whom he asserts to be a lunar deity. This teaching is repeated in the Chick tracts "Allah Had No Son" and "The Little Bride". In 1996 Janet Parshall, in syndicated radio broadcasts, asserted that Muslims worship a moon god. Pat Robertson said in 2003, "The struggle is whether Hubal, the Moon God of Mecca, known as Allah, is supreme, or whether the Judeo-Christian Jehovah God of the Bible is Supreme."
However, recent research from various sources have proven that the "evidence" used by Morey was of the statue retrieved from an excavation site at Hazor, of which there is no connection to "Allah" at all. In fact, Bible scholar and mission strategist Rick Brown openly disagrees with this approach and said:
Those who claim that Allah is a pagan deity, most notably the moon god, often base their claims on the fact that a symbol of the crescent moon adorns the tops of many mosques and is widely used as a symbol of Islam. It is in fact true that before the coming of Islam many "gods" and idols were worshipped in the Middle East, but the name of the moon god was Sîn, not Allah, and he was not particularly popular in Arabia, the birthplace of Islam. The most prominent idol in Mecca was a god called Hubal, and there is no proof that he was a moon god. It is sometimes claimed that there is a temple to the moon god at Hazor in Palestine. This is based on a representation there of a supplicant wearing a crescent-like pendant. It is not clear, however, that the pendant symbolizes a moon god, and in any case this is not an Arab religious site but an ancient Canaanite site, which was destroyed by Joshua in about 1250 BC. ... If the ancient Arabs worshipped hundreds of idols, then no doubt the moon god Sîn was included, for even the Hebrews were prone to worship the sun and the moon and the stars, but there is no clear evidence that moon-worship was prominent among the Arabs in any way or that the crescent was used as the symbol of a moon god, and Allah was certainly not the moon god's name.
Michael Abd El Massih, the Director of Arabic Bible Outreach, echoes the same point and asserts that:
It is an unproven theory, so it may well be false. Even if it turns out to be true, it has little bearing on the Muslim faith since Muslims do not worship a moon god. That would be blasphemy in Islamic teachings. If we use the moon-god theory to discredit Islam, we discredit the Christian Arabic speaking churches and missions throughout the Middle East. This point should not be discounted lightly because the word Allah is found in millions of Arabic Bibles and other Arabic Christian materials. The moon-god theory confuses evangelism. When Christians approach Muslims, they do not know whether they need to convince them that they worship the wrong deity, or to present them the simple Gospel message of our Lord Jesus Christ.
Islamic tradition.
In 8th-century Arab historian Hisham Ibn Al-Kalbi's "Book of Idols", the idol Hubal is described as a human figure with a gold hand (replacing the original hand that had broken off the statue). He had seven arrows that were used for divination.
Some Islamic scholars argue that Muhammad's role was to restore the purified Abrahamic worship of Allah by emphasising his uniqueness and separation from his own creation, including phenomena such as the moon. The miracle of the splitting of the moon shows that God is not the moon, but has power over it. Whether or not Hubal was even associated with the moon, both Muhammad and his enemies clearly identified Hubal and Allah as different gods, their supporters fighting on opposing sides in the Battle of Badr. Ibn Hisham notes that Abu Sufyan ibn Harb, leader of the defeated anti-Islamic army, called to Hubal for support to gain victory in their next battle:
The Sahih al-Bukhari, a written tradition from 9th-century compiler al-Bukhari, clearly differentiates between the worshippers of Allah, and the worshippers of Hubal, referring to the same event.
Muslim views and response.
Most branches of Islam teach that Allah is the name in the Quran used for God, and is the same god worshipped by the members of other Abrahamic religions such as Christianity and Judaism (). Mainstream Islamic thought holds that the worship of Allah was passed down through Abraham and other prophets, but it became corrupted by pagan traditions in pre-Islamic Arabia. Before Muhammad, Allah was not considered the sole divinity by Meccans; however, Allah was considered the creator of the world and the giver of rain. The notion of the term may have been vague in the Meccan religion. Allah was associated with companions, whom pre-Islamic Arabs considered as subordinate deities. Meccans held that a kind of kinship existed between Allah and the jinn. Allah was thought to have had sons and that the local deities of , Manāt and al-Lāt were his daughters. The Meccans possibly associated angels with Allah. Allah was invoked in times of distress. Muhammad's father's name was meaning ""the slave of Allāh".
The Quran itself condemns moon worship. Muslim scholars cite the 37th verse of Sura Fussilat as proof against the moon god claim:
And among His signs are the night and the day and the sun and the moon; do not make obeisance to the sun nor to the moon; and make obeisance to Allah Who created them, if Him it is that you serve. 
In 2009, anthropologist Gregory Starrett wrote, "a recent survey by the Council for American Islamic Relations reports that as many as 10% of Americans believe Muslims are pagans who worship a moon god or goddess, a belief energetically disseminated by some Christian activists." Ibrahim Hooper of the Council on American-Islamic Relations (CAIR) calls the Moon-God theories of Allah evangelical "fantasies" that are "perpetuated in their comic books". Muslim reactions to the allegation are also widespread online.
Farzana Hassan sees these views as an extension of long-standing Christian evangelical claims that Muhammad was an impostor and deceiver: 
Literature circulated by the Christian Coalition perpetuates the popular Christian belief about Islam being a pagan religion, borrowing aspects of Judeo-Christian monotheism by elevating the moon god Hubal to the rank of Supreme God, or Allah. Muhammad, for fundamentalist Christians, remains an impostor who commissioned his companions to copy words of the Bible as they sat in dark inaccessible places, far removed from public gaze.