Of the three Abrahamic Religions, Christianity is the youngest; regardless of this, it is also holds the most followers of any other religion, with over 2 billion people currently ascribing to its set of beliefs. As far as Abraham's part in this goes, he is viewed as an example of faith, whose promise of salvation is seen as having been fulfilled through Christ.

Christianity originated out of Judaism as a result of Jesus of Nazareth's life and teachings, as well as the death and ressurection in C.E. 33. As the story goes, Jesus, having been baptized by the prophet John, is said to have been a healer/teacher that not only saught out to heal individual peoples, but also humanity, beginning with his own kind - the Jews. It is through these teachings that he began to gain a following amongst his fellow Jews. Jesus saw the social barriers and structure currently in place as contradictary to the teachings of Yahweh, the Israelite's God, and so his teachings promoted the disregard of them; instead, he promoted peace among all, even enemies, and no boundaries between men. It was this opposition to the then-adhered structure that led to the conviction and crucifixion of Jesus by the Romans in power.

It is thanks to this crucifixion that Christianity grew and Christ was viewed as a god, for he supposedly arose from the dead/reappeared to his disciples, only in another form that wasn't bound by the physical; what they viewed was more than human, transcending.

It is this belief and blind faith that brought Christianity the momentum it needed to keep growing. Underground meetings were set up, where the words and stories of the transformation that Christianity brings would spread; through the release of 'fear, guilt, and self-centeredness' as brought upon by Jesus' love, the unconditional love of their God, they were able to convey such. With such a powerful new concept, a tool in a way, at their disposal, they were able to grow even moreso.

As far as the church is concerned, the original notion was that each person was an 'invisible church' - that is, their body is an extention of God, in a way. As Jesus said, "I am the vine, you are the branches"; Jesus is God, and the Holy Spirit flows through them.

There is also the visible church, which essentially evolved into the three main factions today - Roman Catholicism, Eastern Orthodoxy, and Protestantism. The meetings were essentially underground until 313 AD when it became legally recognized in Rome; by 380 AD it became the official religion. By 1054 it had it's first split into Roman Catholicism and Eastern Orthodoxy. In the 16th century with the Protestant Reformation it split again.