Today is the feast of St. Cyril of Jerusalem, Doctor of the Church. From his Catechetical Lectures, Lecture 18:
The root of all good works is the hope of the Resurrection; for the expectation of the recompense nerves the soul to good works. For every labourer is ready to endure the toils, if he sees their reward in prospect; but when men weary themselves for nought, their heart soon sinks as well as their body. A soldier who expects a prize is ready for war, but no one is forward to die for a king who is indifferent about those who serve under him, and bestows no honours on their toils. In like manner every soul believing in a Resurrection is naturally careful of itself; but, disbelieving it, abandons itself to perdition. He who believes that his body shall remain to rise again, is careful of his robe, and defiles it not with fornication; but he who disbelieves the Resurrection, gives himself to fornication, and misuses his own body, as though it were not his own. Faith therefore in the Resurrection of the dead, is a great commandment and doctrine of the Holy Catholic Church; great and most necessary, though gainsaid by many, yet surely warranted by the truth. Greeks contradict it , Samaritans disbelieve it, heretics mutilate it; the contradiction is manifold, but the truth is uniform.
Although he himself seems to have been orthodox his entire career, he was for a long while at least very sympathetic to Semi-Arianism, and appears to have been willing to allow for the possibility that the Nicene party of orthodoxy was being excessively intolerant. However, long disputes with other bishops over the matter seems to have slowly convinced him that the Semi-Arians were not acting or speaking in good faith; he was a Conciliar Father at the First Council of Constantinople, where for the first time that we know of in his career he came down firmly against the Semi-Arian position and voted for the homoousios. His Catechetical Lectures, delivered while Bishop of Jerusalem, are some of the most important catechetical works in the course, and the gold standard for catechesis prior to the rise of catechetical innovations in the Reformation and Counter-Reformation. He is also quite important, in his later Mystagogical Lectures, for the theology of the sacraments (particularly baptism, confirmation, and eucharist), of which he has a very robust view.
