For the early Christians the teaching of Jesus was showing them a new way of living and touching their deepest human needs. The life of Jesus signals the beginning of the Christian era with his death thought to have been around AD 30-33, and his birth date being used to locate the start of the first millennium. Jesus himself left no writings but his life and teachings are recorded in the four gospels. Matthew, Mark, Luke and John and the effects of his teachings on the culture at that time are recorded in the remaining books of the New testament, particularly in Acts.
Many of these books took the form of letters often known as the epistles written by the apostle Paul to believers in the early church, these give guidance to ensure that the teachings are followed properly raising issues of conduct and suggesting corrective measures. These letters were ultimately important in establishing the theology of the church. The teachings of Jesus were impressive and very counter cultural for the time, they ground breaking in addressing power both religious and political, and challenging attitudes toward women, the poor and marginalised, particularly vulnerable groups such as orphan’s widows and the sick.
They addressed the person in areas such as pride, ego and moral behaviour pointing people toward humility, sharing resources, service to others and a willingness to sacrifice selfish desires and accept the reality of suffering. Some of his richest teachings are found in the sermon on the mount and in the parables. There was clearly hardship involved in being obedient to God but they were all in it together. Christians were to be one united body, in community and in God. He left one ritual for his followers to practice which was the Agape Love meal of bread and wine which the new believers were to share with one another.
These teachings along with his many miracles and healing's and the resurrection made him both a revered and hated figure but for his devotees he was an inspirational person who had made available the power of the Holy spirit which was the driving force for them to take his message to the ends of the earth. They were transformed from being timid and frightened to being brave and bold and in the process were prepared to endure great hardships including beatings, imprisonment, torture and death. He was not asking his followers to endure anything that he had not, for he too had been an innocent man unjustly dealt with. To them he was the visible manifestation of the invisible God and through him salvation and a changed and redeemed life could be possible. It was their mission to share this good news with others. The life of Jesus was their inspiration, the focal point for faith and the source of Christian history.
Summary and references from: Christian history- Alister E. Mc Grath