Christianity is the largest religion in the world. Its members are split between Catholics, Protestants and Orthodox Christians, although there are literally thousands of denominations within each division, each with their own ideas about how Christianity should manifest itself.
Christianity takes its name from Jesus Christ. It is based on the Old Testament and New Testament, with emphasis on the writings of the apostle Paul. Paul's writings constitute a substantial amount of the New Testament. It is considered an Abrahamic religion along with Judaism and Islam.
"There ought to be a term that would designate those who actually follow the teachings of Jesus, since the word 'Christian' has been largely divorced from those teachings, and so polluted by fundamentalists that it has come to connote their polar opposite: intolerance, vindictive hatred, and bigotry." —Philip Stater