In Book II of his De fide orthodoxa (On the Orthodox Faith), St. John Damascene (ca. 645-749) shows how each person is free to act in a universe ruled by Divine Providence.
St. John makes this distinction between good and evil acts: “The choice of what is to be done is in our own hands: but the final issue depends, in the one case when our actions are good, on the cooperation of God, Who in His justice brings help according to His foreknowledge to such as choose the good with a right conscience, and, in the other case when our actions are to evil, on the desertion by God, Who again in His justice stands aloof in accordance with His foreknowledge.”
He distinguishes between what pleases God and what otherwise God permits: “God’s original wish was that all should be saved and come to His Kingdom (1 Tim 2:4). For it was not for punishment that He formed us but to share in His goodness, inasmuch as He is a good God. But inasmuch as He is a just God, His will is that sinners should suffer punishment. The first then is called God’s antecedent will and pleasure, and springs from Himself, while the second is called God’s consequent will and permission, and has its origin in us.” (29)
He distinguishes between prescience and predetermination: “We ought to understand that while God knows all things beforehand, yet He does not predetermine all things. For He knows beforehand those things that are in our power, but He does not predetermine them.”
He explains what in natural and unnatural for us: “We have it in our power either to abide in virtue and follow God, Who calls us into ways of virtue, or to stray from paths of virtue, which is to dwell in wickedness, and to follow the devil who summons but cannot compel us. For wickedness is nothing else than the withdrawal of goodness, just as darkness is nothing else than the withdrawal of light. While then we abide in the natural state we abide in virtue, but when we deviate from the natural state, that is from virtue, we come into an unnatural state and dwell in wickedness.”
Finally, he notes: “Repentance is the returning from the unnatural into the natural state, from the devil to God, through discipline and effort.” (30)
Quotations from A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church, Second Series, Vol. IX, ed. Philip Schaff and Henry Wace (Edinburgh: T&T Clark, 1886).