Bultmann
The hypothesis of the Gospel of John being composed in layers over a period of time had its start with Rudolf Bultmann in 1941. Bultmann suggested that the author(s) of John depended in part on an author who wrote an earlier account. This hypothetical "Signs Gospel" listing Christ's miracles was independent of, and not used by, the synoptic gospels. It was believed to have been circulating before the year 70 AD. Bultmann's conclusion was so controversial that heresy proceedings were instituted against him and his writings.
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