It is a fallacy to hold that the New Testament must be explicable in terms of its background. There is a radical novelty in Christianity and it is always possible that the New Testament writers mean something different from others even when they adapt common matter. John, for example, makes use of the Logos concept but we cannot find his meaning in his literary predecessors. No great writer, biblical or non-biblical, ancient or modern, is completely explicable in terms of the context in which he writes. A great writer invariably outstrips his contemporaries and brings new meaning to light. It may be possible to discover the sources of a creative writer. But that does not dispose of his creativity. He goes beyond his source.
Leon Morris, “The Emergence of the Doctrine of the Incarnation: Review Article,” Themelios, No. 1, September 1982 8 (1982): 16.