Jonathan Edwards thought it was impossible. He suggests in Nature of True Virtue,
Therefore he that has true virtue, consisting in benevolence to being in general, and in benevolence to virtuous being, must necessarily have a supreme love to God, both of benevolence and complacence. And all true virtue must radically and essentially, and as it were summarily consist in this. Because God is not only infinitely greater and more excellent than all other being, but he is the head of the universal system of existence; the foundation and fountain of all being and all beauty; from whom all is perfectly
derived, and on whom all is most absolutely and perfectly dependent; of whom, and through whom, and to whom is all being and all perfection; and whose being and beauty are, as it were, the sum and comprehension of all existence and excellence: much more than the sun is the fountain and summary comprehension of all the light and brightness of the day.
Aristotle concedes that to be virtuous one must have a disposition toward virtue. For him virtues are learned through practice.
Then there must be, to begin with, a kind of affinity to Virtue in the disposition; which must cleave to what is honourable and loath what is disgraceful. But to get right guidance towards Virtue from the earliest youth is not easy unless one is brought up under laws of such kind; because living with self-mastery and endurance is not pleasant to the mass of men, and specially not to the young.
Practice, however, seems to contribute no little to its acquisition; merely breathing the atmosphere of politics would never have made Statesmen of them, and therefore we may conclude that they who would acquire a knowledge of Statesmanship must have in addition practice.
Practice of virtues is important. Ethics take place in community. However, avoidance of subjectivity in practice comes from knowledge of virtues’ origin. Lack of awareness of virtue’s origin cripples one’s ability to perform a virtuous act. Here, Edwards is helpful because apart from a claim that virtue emanates from a divine character, one is relegated to at least a subjective perspective of virtues, possibly a coherence perspective on virtues. Edward’s claim that virtue originates with the divine nature of the Creator God provides a correspondence between the character of the Creator God and the expected character of those God created in his image. Edwards, in other works, will complete his thoughts of God’s expectations of his created by suggesting that a true virtuous task is impossible apart from the penetrating work of the Holy Spirit in a regenerated person’s life.
 Edwards, Jonathan. Nature of true virtue (Kindle Locations 282-288). [Ann Arbor]: University of Michigan Press.
 Aristotle (2005-07-01). Nichomachean Ethics (Kindle Locations 3706-3709). Public Domain Books. Kindle Edition.