The three largest groups of Christians are the Catholic Church, Protestantism, and the Eastern Orthodox Church.
The largest Christian denomination is the Catholic Church, with 1.09 billion adherents. The second largest Christian branch is Protestantism or the Eastern Orthodox Church (Protestants are often divided into multiple denominations).
Christianity is the predominant religion in Europe, Russia, the Americas, the Philippines, East Timor, Southern Africa, Central Africa, East Africa and Oceania. There are also large Christian communities in other parts of the world, such as Indonesia, Central Asia and the Middle East, where Christianity is the second-largest religion after Islam. America has the largest Christian population in the world, followed by Brazil and Mexico.
The second largest religion in the world is Islam, with 1.6 billion followers. The main regions of Islam are: Middle East, Northern Africa, Central Asia, South Asia, Western Africa, Maritime Southeast Asia with large population centers existing in Eastern Africa, Balkan Peninsula, Russia and China. The Islamic Holy Book is the Quran.
Both Christianity and Islam are considered Abrahamic religions. Abrahamic religions emphasize and trace their common origin to the tribal patriarch Abraham. Judaism, Christianity and Islam are the largest Abrahamic religions in terms of numbers of adherents.
The major Abrahamic religions in chronological order of founding are:
- Judaism (seventh century BCE - Before the Common Era)
- Christianity (first century CE)
- Islam (seventh century CE)
Abrahamic religions with fewer adherents include Rastafari, Samaritanism (sometimes classified as a branch of Judaism), the Druze faith (often classified as a branch of Isma'ili Shi'i Islam), Bábism, and the Bahá'í Faith.
The first of the Crusades began in 1095 (1096-99), when armies of Christians from Western Europe responded to Pope Urban II’s plea to go to war against Muslim forces in the Holy Land. After the first Crusade achieved its goal with the capture of Jerusalem in 1099, the invading Christians set up several Latin Christian states, even as Muslims in the region vowed to wage holy war (jihad) to regain control over the region.
- Second Crusade (1147-49)
- Third Crusade (1189-92)
- Fourth-Sixth Crusades (1198-1229)
The remainder of the 13th century saw a variety of Crusades aimed not so much at toppling Muslim forces in the Holy Land, but to combat any and all of those viewed as enemies of the Christian faith.
Reference: Crusades
