Cyril (c. 315 – 387) was made Bishop of Jerusalem in c. 349 A.D. in a time of turbulence for the Church. He was passionate about truth, and because of his refusal to compromise with the Arian heresy, he was exiled on three separate occasions. Cyril is best known for his Catechetical Lectures, transcribed by one of his hearers. These comprise one of the most systematic presentations of Christian doctrine of the patristic era. Here his argument illustrates the pastoral value of doctrine: a correct doctrine of God is the antidote to the fatal disease of idolatry.
Seeing then that many have gone astray in divers ways from the One God, some having deified the sun, that when the sun sets they may abide in the night season without God; others the other parts of the world; others the arts; others their various kinds of food; others their pleasures; while some, mad after women, have set up on high an image of a naked woman, and called it Aphrodite, and worshipped their own lust in a visible form; and others dazzled by the brightness of gold have deified it and all other kinds of matter;—whereas if one lay as a first foundation in his heart the doctrine of the unity of God, and trust to Him, he roots out at once the whole crop of the evils of idolatry, and of the error of the heretics: lay thou, therefore, this first doctrine of religion as a foundation in thy soul by faith.1
1 Cyril of Jerusalem, Catechetical Lectures, in The Nicene and Post-Nicene Fathers, 2nd Series, vol. 7, trans. Edward H. Gifford (1893; reprint, Grand Rapids, MI: Wm. B. Eerdmans Publishing Company, 1996), 20.