And as for such a claim, the case is not simply whether or not Paul claimed that Jesus "had become flesh". Indeed virtually every person in the Jewish scriptures is portrayed as a real flesh and blood person, yet today it is widely accepted that the majority of figures from the Torah were purely mythical. Moses, Abraham, Noah, etc., etc., all mythical. We don't conclude that they were mythical because we found documents claiming that they were entirely spiritual, but rather because of the nature of the stories and how the stories are now known to have been written.