1 Corinthians 11:19

There must be also heresies: By reason of the pride and perversity of man's heart; not by God's will or appointment; who nevertheless draws good out of this evil, manifesting, by that occasion, who are the good and firm Christians, and making their faith more remarkable. (Challoner) --- Not that God hath directly so appointed, as necessary: this originates in man's malice, and his sole pride, and great abuse of free-will. The providence of God draweth good out of evil, but wo to the man, says the Scripture, by whom scandal cometh, such as sects and heresies. Hence St. Augustine, chap. viii. de vera relig. says: "Let us use heretics not so as to approve their errors, but to make us more wary and vigilant, and more strenuous in defending Catholic doctrine against their deceits."