How many and which Gospels were discarded when the New Testament was compiled?

Answer 1

We now know of quite a few early gospels that were not included in the New Testament, most of them being from gnostic Christianity. In its earliest days, Christianity was divided into several different branches, with each holding quite different views about the nature of Jesus, the nature of God and the role of Christianity. One of these various branches gradually outgrew the others and became the dominant form of Christianity. Each branch and sect of Christianity had its own gospels and other scriptures, although most of them came to share Paul's epistles as a common basis of their belief. Naturally the dominant Christians, now known to some scholars as proto-Catholic-Orthodox, chose those gospels that most closely reflected their understanding of Jesus. It was this group that compiled a set of scriptures now known as the New Testament.

The New Testament Christians were closely aligned to the synoptic gospels, and these were a natural choice. John's Gospel is believed by some to have been written in a gnostic milieu, but amended to make it more acceptable to the mainstream Church. Another formerly gnostic gospel that was considered for inclusion in the New Testament is the Gospel of Thomas, possibly one of the oldest gospels. Eventually all other gospels were condemned as heretical.