History. Christians believe that Jesus Christ is the Son of God, and the Christian religion is based on his life and teachings. Christians believe that by sacrificing his son, God gave them salvation and the chance of everlasting life. After the crucifixion of Jesus his disciples preached to the Jewish people of the eastern Mediterranean and wrote down their beliefs as scriptures. Later, the work of St. Paul caused Christianity to grow in the Roman empire. Christianity developed two branches: western, based in Rome (the origin of the Roman Catholic Church), and eastern, based in Constantinople (Istanbul)(the origin of the Orthodox Churches). In more recent times, the Reformation caused a third branch of Christianity to develop known as Protestantism. Now there are almost 2 billion Christians throughout the world.
Beliefs and Practices. Christianity developed from Judaism and has similar beliefs in that there is one God and that God would send a Messiah. However, the similarity ends there as the Jewish faith does not believe, as do Christians, that Jesus is the Son of God, and that his death and resurrection began a covenant between God and humans. Christians generally believe salvation is possible for all who believe in Jesus and who live according to his teachings. The various branches of Christianity, however, vary as to the exact nature of this belief. Christians believe in one God, who exists in three forms - Father, Son and Holy Spirit - comprising the Holy Trinity.
Calendar. The Christian faith has three separate calendars, the Western, the Orthodox New Calendar and the Orthodox Old Calendar. The Western Calendar is that of the Roman Catholic and Protestant Churches. The Orthodox New Calendar is the same as the Western Calendar for all fixed feasts but uses the old or Julian calendar for moveable feasts such as Easter and is used primarily by the Greek and Cypriot Orthodox Churches. The Orthodox Old Calendar is the Julian Calendar and is used by most other Orthodox churches and also by the Coptic church and most churches in the Middle East.
For a perpetual calendar calculating the Western and Orthodox moveable feasts in perpetuity see the Ecclesiastical calendar by Marcos Montes:
http://www.smart.net/~mmontes/ec-cal.html
Holidays. The most important Christian holidays are Christmas and Easter, celebrating the birth and resurrection of Jesus Christ. The various branches of Christianity celebrate a variety of other holidays, depending on the particular country and branch of Christianity.
Web sites concerning Christianity include: