Morey argues that "Allah" was the name of a moon god 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.[4] Joseph Lumbard, a professor of classical Islam, has stated the idea is "not only an insult to Muslims but also an insult to Arab Christians who use the name 'Allah' for God."[5]