James McGrath, in his published dissertation, John's Apologetic Christology (which just happens to be directly relevant to my thesis), makes a point that should be obvious but is too easily forgotten:
[A] century was just as long in the ancient world as it is today, and for this reason it is simply unjustified to assume that what was controversial in the third and subsequent centuries was controversial in the first century. Thus, in much the same way that one would be cautious in reading the Synoptics in light of John, much less in light of the council of Nicaea, so one must be cautious of reading first-century sources in light of the views held by rabbis of the third and subsequent centuries. (pg. 73)And of course, the same applies to the New Testament itself: the time between the 30s (when Jesus taught), the 50s (when Paul wrote) and the 90s (when John's Gospel reached its final form) was just as long in the first century as it was in the twentieth.