There were several religious practices in Mecca before Muhammed and the start of Islam. For example, some people followed a polytheistic religion. Arab polytheism involved worshipping deities such as Hubal at the Kaaba in Mecca. The Kaaba, a granite cube that is Islam's holiest site, was, in the time before Muhammed, the location of hundreds of idols, according to some historians.
In addition, various forms of Christianity were practiced in Mecca, including Miaphysitism (which maintains that Jesus Christ, humanity, and God are one), and its rival sect of Christianity, Nestorianism (which maintains that there is a separation between the human and divine forms of Jesus Christ). Judaism was also practiced in the region, as Jews had migrated to the area since the Roman era, as was Zoroastrianism, the religion practiced in Iran before Islam.
There was a diverse religious culture that existed in the Arabian peninsula during the period before Muhammad’s revelation. The most common practice was Arab polytheism. The pantheon of gods in this system was extensive, with each city and area worshiping different chief gods. A trinity of goddesses was central to the practices of the polytheists as they were believed to be the daughters of an important god. There was a certain degree of mysticism involved in the practice with a belief in spirits, djinn, and demons. Idolatry was a key facet of the religion and the important Islamic site, the Kaaba, had hundreds of idols that were worshiped. The Persian Zoroastrian religion seems to have had an important influence in Arabia, especially the notion of duality.
On a smaller scale, other religions were influential in the city of Mecca. After 70 AD, the Romans exiled Jews from their homeland, and thousands made their way to the Arabian peninsula. The Romans introduced and converted Arabs to the north to Christianity. The Arabs in the south were influenced by Christianity through the conquests of the Kingdom of Aksum (Ethiopian) in Yemen. Christianity and Judaism played only a minor role in the religious heritage of Mecca.
Another monotheistic belief system in Mecca centered around the adoration of the Prophet Abraham. The religion worshiped only one god: the god of Abraham. Unsurprisingly, this was the religious practice of the Prophet Muhammad’s family.