Judaism
For Jewish people it is Judaism is not just a matter of religion but their historic background and life. Jews believe themselves to be descended from Abraham, to whom God promised a land “unto thee, and to thy seed after thee”. Judaism traditionally passes through the female line or by conversion, different Jewish movements (Orthodox, Conservative, Reform) having different require “guidance”.
Christianity
To the followers of Jesus of Nazareth, he was more than just a prophet; he was the Son of God who brought a new covenant replacing the Old Testament given to Abraham. His Crucifixion in Jerusalem came to be seen as self-sacrifice for the salvation of humankind and inspired a new religious movement based on his teachings. At first this existed as a subsect of Judaism; Jesus came to be known as Christ (Christos: the anointed one, in Greek), as he was held to be the Messiah of Jewish prophecies. However, the new religion spread far beyond Judaea. It saw persecution, then recognition by the Roman Empire, eventually becoming its dominant religion in the 4th century AD.
Islam
Islam was founded by Muhammad, a former merchant from Mecca in Arabia. Born around AD 570, at the age of 40 he began to receive revelations of the word of Allah. These continued for the rest of his life and were transcribed as the Quran. Muhammad’s preachings were not well received in Mecca and in 622 he and his followers were forced to flee for Medina. This flight, or hejira, constitutes year zero in the Islamic calendar. Before Muhammad died in 632, he had returned to conquer Mecca. Within a further four years, the armies of Islam had swept out of the Arabian Desert and conquered the Holy Land.