From PBS Global Connections
Jews believe in one god and his prophets, with special respect for Moses as the prophet to whom God gave the law. Jewish law is embodied in the Torah (also known as the Pentateuch) and the Talmud (collected commentary on the Torah completed in the fifth-century C.E.).
Judaism is more concerned with actions than dogma. In other words, observance of rules regulating human behavior has been of more concern than debates over beliefs in the Jewish tradition. According to Orthodox Judaism, Jewish law, or halakhah, includes 613 commandments given by God in the Torah, as well as rules and practices elaborated by scholars and custom. Jewish law covers matters such as prayer and ritual, diet, rules regulating personal status (marriage, divorce, birth, death, inheritance, etc.), and observance of holidays (like Yom Kippur, the Day of Atonement; and Passover, the feast celebrating the exodus of the Jews from slavery in Egypt).
In the United States, debate over the necessity of observing Jewish law has led to the development of three major movements. Orthodox Jews believe that Jewish law is unchanging and mandatory. Conservative Jews argue that God's laws change and evolve over time. Reform and Reconstructionist Jews believe that these laws are merely guidelines that individuals can choose to follow or not. In addition, there are many Jews in the United States who are secular or atheist. For them, their Judaism is a culture rather than a religion.
Jews do not believe in the prophets after the Jewish prophets, including Jesus and Muhammad. Therefore, they do not subscribe to the idea that Jesus was the Messiah and the son of God, nor do they believe in the teachings of Islam.
Christianity developed out of the monotheistic tradition of Judaism; Jesus, its founder, was a member of the Jewish community in Roman Palestine. Its holy scriptures are the Old Testament (the Jewish Torah with additions), and the New Testament (written by the followers of Jesus after his death and containing the life story of Jesus and other early Christian writings).
Christians believe that God is revealed through three dimensions: the Father, the Son (Jesus Christ), and the Holy Spirit. Jesus is considered the son of God, born to the virgin Mary and come to Earth to offer redemption for mankind's sins. After Jesus was crucified and executed by the Romans, he rose from the dead and ascended into heaven. This event is celebrated at Easter, while the birth of Jesus is celebrated at Christmas.
Christians believe in an afterlife where those who have lived a good life will reside in heaven with God, and those who have lived an unrepentant life of sin will be punished in hell.
Although Christianity developed out of Judaic texts, Christians do not follow Jewish law. Instead, they believe that the ritualistic Jewish law was abrogated in favor of a universal gospel for all of humanity and the Christian teaching, "Love thy neighbor as thyself."
Muslims believe that Allah (the Arabic word for God) sent his revelation, the Quran, to the prophet Muhammad in the seventh century C.E. to proclaim it to mankind. The Quran contains verses (surahs) in Arabic that tell Muslims to worship one god, and explains how they should treat others properly.
Another historical text, the Hadith, written by scholars after the death of Muhammad, describes Muhammad's life as an example of pious behavior, proscribes law for the community based on the Quran and the example of Muhammad, and explains how certain rituals should be performed.
Observant Muslims practice five principles (pillars) of Islam: orally declaring their faith (shahadah); praying five times a day (salat); fasting in the daylight hours during the month of Ramadan (sawm); giving a share of their income for charity (zakat); and making a pilgrimage to Mecca at least once in their lifetime if they can afford it (hajj). Many Muslims also observe dietary rules, in origin similar to those of Judaism, that forbid certain foods (like pork), outlaw alcohol, and dictate how animals should be slaughtered for food.
The Muslim calendar is lunar, and shifts in relation to the solar calendar. Just as Christians count years starting with the year of Jesus's birth, Muslims count years beginning with Muhammad's move from Mecca to Medina in 622 C.E. Muslim years are labeled as A.H., Anno Hegirae, or "year of the Hijra."
Major Muslim festivals include Id al-Fitr (the Fast-Breaking Festival, celebrated at the end of Ramadan) and Id al-Adha (the Festival of Sacrifice, the commemoration of Abraham's willingness to sacrifice Ishmail which takes place during the month of pilgrimage).
Muslims believe in a Day of Judgment, when righteous souls will go to heaven and wrongdoers will go to hell.
Islam sees Judaism and Christianity as earlier versions of Islam, revelations given within the same tradition by Allah but misunderstood over time by their followers. Muslims see Islam as the final, complete, and correct revelation in the monotheistic tradition of the three faiths.
The Islamic tradition recognizes many of the Jewish and Christian prophets, including Abraham, Moses, and Jesus (although he is not considered to be the son of God). Many non-Muslims mistakenly believe that Muhammad is the equivalent of Jesus in the Islamic tradition; in fact, it is the Quran that stands in the same central position in Islam as Jesus does in Christianity. Muhammad himself is not divine, but a prophet chosen by God to deliver his message and an example of piety to emulate.
Full article: Three Religions, One God