Theanswer to this question depends on belief as well as the research of historians. Muslims believe that Islam existed from the beginning of creation and that the Koran was written in heaven and dictated to Muhammad. There is little that Muhammad and the Islamic religion would have borrowed from Christianity.
However, Philip Jenkins (The Lost History of Christianity) says that the Christian impact on Islam was profound, and can be traced at the deepest roots of that faith.
Mosques look as they do because their appearance derives from that of Eastern Christian churches in the early days of Islam. Jenkins says that most of the religious practices of the believers within those mosques stem from the example of Eastern Christians, including the prostrations that appear so alien to modern Westerners.
The severe self-denial of Ramadan was originally based on the Eastern practice of Lent.
The Quran itself often shows startling parallels to Eastern Christian scriptures, devotional texts, and hymns. Some scholars have even argued that much of the text originated in Syriac lectionaries, collections of readings for church use.
Much of Islamic theology parallels that of Christianity or Judaism, but of course this does not prove that Muhammad adapted Christian and Judaic beliefs, rather than simply receiving them from heaven.
Judaism and Christianity don't relate to Mohammad.
Judaism and Christianity.
Christianity and Islam are both built on several concepts which they borrow from Judaism.
Christianity and Judaism
Islam, Judaism and Christianity.
Christianity and Islam both have roots in Judaism. Abraham's son Issac was the ancestor of Jesus. Abraham's son Ishmael was the ancestor of Muhammad.
Muhammad plays no role in Judaism. At the point he lived, Judaism had existed for almost 2000 years.
Muslims are the followers of Islam that is the religion of Allah (or God in English and same God in Christianity and Judaism). Islam is the oldest God religion in the universe. Islam means full submission to God and to His will. Islam per Torah revelation to Moses is called Judaism. Islam per the Bible revelation to Jesus is called Christianity. Islam per Quran revelation to Muhammad is called the same name Islam as it is the last God religion on earth. Accordingly, Muslims (per Quran revelation to prophet Muhammad) didn't get anything from Judaism and or Christianity. The three religions got their teachings, ritual worships, and morals from the same source that is Allah (or God in English and same God in Christianity and Judaism).
The Pope has called Judaism "Christianity's older sister," since Christianity bases much of its content on Judaism.
Christianity does not struggle with Judaism.
Judaism, Christianity, and Islam have all claimed the Holy Land for themselves.
Several religions evolved from the Hebrew religion, including Christianity and Islam. Christianity emerged from the teachings of Jesus Christ, who was a Jewish preacher. Islam was founded by the Prophet Muhammad, who was influenced by both Jewish and Christian beliefs. Both Christianity and Islam share common roots with Judaism, including the belief in one God and the importance of ethical living based on divine laws.