Arthur Darby Nock (1902-1963), St. Paul
(New York: Harper & Brothers Publishers, 1937), p. 13:
The Pauline Epistles are extraordinarily difficult to interpret. Read in English, in the light of Scripture teaching and sermons in church, they have a certain deceptive familiarity and naturalness, although, to be sure, it is a fair question how many of those who have attended the Anglican burial service can attach much meaning to the prescribed reading from I Cor. xv. If we approach these letters in the original Greek, and come to them from the reading of other Greek texts of the period, there is not a paragraph which does not pull us up with a start as containing something which is, from that standpoint, barely intelligible.
Id., p. 236:
A great classical scholar, Eduard Norden, has remarked, 'Paul is a writer whom I, at least, understand only with very great difficulty.' Probably all classical scholars would agree.