Christianity unites all people believing in that, that Jesus Christ is God coming in fleshes for the rescue of the world. From what must be the world is saved? From a sin, curse and death, or, in other words, from all forms of evil.
In the first millennium of existence of Church christianity was only Orthodox.
At the beginning of the second millennium of way of development of christianity on East and the West sent to such degree, that practically not communicating inter se churches appeared: East and Western.
Orthodoxy saved unchanging the dogma formed in the first millennium, and to our time.
Catholicism in a sufficient degree deviated from the Orthodox dogma.
Arising up in the sixteenth century, anti- catholic motion is -Reformation- resulted in appearance of the third direction in christianity - protestantism.
The main consists of that, that all now existent christian flows were distinguished from Orthodoxy the dogma of that to this day remained unchanging from apostolic times.