As opposed to the Christian God, other gods have been proposed throughout the history of mankind. The term god is applied in a general sense to any deity that is worshiped as part of a theistic belief system.
Notes
It is claimed that Christianity, Islam, and Judaism worship the same God in different ways. This claim is regarded by some as a way to convert Jews and Christians to Islam, since it supports the idea that Abrahamic religion has "grown" from Judaism to Christianity to Islam.[1] However, many are skeptical of this idea.[2]
Regardless of the lack of historical data regarding the origins of any of these three religions, the mythological links between them are clear. It is a tenet of the Jewish religion that all Jews descended from Abraham (indeed, in order to convert to Judaism one must complete an 'adoption' ritual for the house of Israel); as Jesus is regarded as Jewish, the growth of Christianity as an offshoot of the Jewish religion is clear. In a similar fashion, Muslims claim to be descended from Abraham by way of Ishmael.