Saint Cyril of Jerusalem

For the method of godliness consists of these two things, pious doctrines, and virtuous practice: and neither are the doctrines acceptable to God apart from good works, nor does God accept the works which are not perfected with pious doctrines. For what profit is it, to know well the doctrines concerning God, and yet to be a vile fornicator? And again, what profit is it, to be nobly temperate, and an impious blasphemer? A most precious possession therefore is the knowledge of doctrines: also there is need of a wakeful soul, since there are many that make spoil through philosophy and vain deceit.  The Greeks on the one hand draw men away by their smooth tongue, for honey droppeth from a harlot’s lips:  whereas they of the Circumcision deceive those who come to them by means of the Divine Scriptures, which they miserably misinterpret though studying them from childhood to old age, and growing old in ignorance . But the children of heretics, by their good words and smooth tongue, deceive the hearts of the innocent,  disguising with the name of Christ as it were with honey the poisoned arrows  of their impious doctrines : concerning all of whom together the Lord saith, Take heed lest any man mislead you.  This is the reason for the teaching of the Creed and for expositions upon it.

Cyril of Jerusalem (2013-03-08). The Catechetical Lectures of St. Cyril of Jerusalem (Kindle Locations 819-831).  . Kindle Edition.