Christianity originated with the ministry of Jesus in the 1st-century Roman province of Judea. According to the Gospels, Jesus was a Jewish teacher and healer who proclaimed the imminent Kingdom of God and was crucified at c.30–33 AD. His followers believed that he was raised from the dead and exalted by God, and would return soon at the inception of God's Kingdom.
The earliest followers of Jesus were apocalyptic Jewish Christians. Due to the inclusion of Gentiles, the developing early Christian Church gradually grew apart from Judaism and Jewish Christianity during the first two centuries of the Christian Era.
In 313, Emperor Constantine I issued the Edict of Milan, officially legalizing Christian worship. In 380, with the Edict of Thessalonica put forth under Theodosius I, the Roman Empire officially adopted Trinitarian Christianity as its state religion, and Christianity established itself as a predominantly gentile religion in the state church of the Roman Empire.
Christological debates about the human and divine nature of Jesus consumed the Christian Church for a couple of centuries, and seven ecumenical councils took place to resolve these debates. Arianism was condemned at the Council of Nice (325), which supported the Trinitarian doctrine as expounded in the Nicene Creed.
In the early Middle Ages, missionary activities spread Christianity towards the west among German peoples. During the High Middle Ages, eastern and western Christianity grew apart, leading to the East-West Schism of 1054. Growing criticism of the Roman Catholic ecclesiological structure and its behavior led to the Protestant movement of the 16th century and the split of western Christianity.
Since the Renaissance era, with western colonialism, Christianity has expanded throughout the world. Today there are more than two billion Christians worldwide, and Christianity has become the world's largest religion.