Canon & Orthodoxy

Helmut Koester and a number of others in recent years (and
earlier, Walter Bauer) have shown rather decisively, I think,
that early Xty (the 1st several centuries) were anything but a
main stream "orthodoxy" surrounded by fringe "heretical" groups. 
One could argue just as well that the canon "made" orthodoxy, as
vice versa.
Whether Gos. Thomas is gnostic is no more clear than whether Gos.
John is.
George Aichele