1 Corinthians 8:2

And then he adds a third consideration, which was of force to set them down. What then is this? that although charity be joined with it, yet not even in that case is this our knowledge perfect. And therefore he adds, "But if any man think that he knoweth any thing, he knoweth nothing yet as he ought to know." This is a mortal blow. "I dwell not," saith he, "on the knowledge being common to all. I say not that by hating your neighbor and by arrogance, you injure yourself most. But even though you have it by yourself alone, though you be modest, though you love your brother, even in this case you are imperfect in regard of knowledge. For as yet thou knowest nothing as thou oughtest to know." Now if we possess as yet exact knowledge of nothing, how is it that some have rushed on to such a pitch of frenzy as to say that they know God with all exactness? Whereas, though we had an exact knowledge of all other things, not even so were it possible to possess this knowledge to such an extent. For how far He is apart from all things, it is impossible even to say. And mark how he pulls down their swelling pride: for he said not, "of the matters before us ye have not the proper knowledge," but, "about every thing." And he did not say, "ye," but, "no one whatever," be it Peter, be it Paul, be it any one else. For by this he both soothed them and carefully kept them under.