When there is a question of what is sinful and what isn’t, there usually are certain acts that do not always have a yes-no kind of reply as to their moral quality. Drinking is one of those. There are a couple of factors to be considered by the individual to determine if drinking as much as they do constitutes a sin, a mortal one.
Again, the final judgement as to the moral quality of actions may not always lie with people like us who try to explain what is good and bad, but with each person’s informed conscience since we cannot really interpret the commandments of God in the context of individual concrete situations (which play serious role in constituting moral evil, in diminishing or increasing their gravity and culpability). So the discourse here is on an objective level and bears tinctures of personal opinion too.
However, insofar as morality goes there is always a certain “general ground” of discernment that catches many people’s situation and that is what we’re going to try to establish here. Each person needs to be open to their confessors as to their consumption of alcohol and other substances so they’d be guided as to the moral quality of their actions and ways to receive freedom in cases of abuse and addiction.
Factors to Consider:
According to St Thomas Aquinas, drunkenness isn’t always sinful mortally, in some cases it isn’t sinful at all to be drunk, but the factors below affect the moral quality of each situation.
1. The Wine is too strong but the drinker does not know: this does not constitute a mortal sin since the drinker needs be well aware of what they’re doing before it becomes morally wrong. If like Noah (Gen. 9) Someone is deceived or forced to drink, the evil of the act is diminished or entirely removed since there is no foreknowledge or free choice involved.
2. Drinker knows wine is strong but not how much: One could freely drink wine without knowing how strong it is. They know it is alcoholic but no idea a little of it could make them drunk or how much they’re supposed to take. This happens to those who are new to drinking. This at best could constitute a venial sin since somehow there’s no perfect knowledge and foresight.
3. Full Knowledge, full consent: A person who freely decides to get drunk sins mortally since anything we freely choose that deprives us of our use of reason puts us and others in moral and physical danger. And this in itself is sinful. When one knows his drinking to be both immoderate and intoxicating, this is a sin grouped with gluttony.
Drinking is good, alcohol, like food is a gift of God, but must be used with moderation and gratitude.
"Be very careful, then, how you live—not as unwise but as wise, making the most of every opportunity, because the days are evil. Therefore do not be foolish, but understand what the Lord's will is. Do not get drunk on wine, which leads to debauchery. Instead, be filled with the Spirit."
Now the works of the flesh are manifest, which are these: Adultery, fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings, and such like; which I denounce, as I have also told you in time past that those who do such things shall not inherit the kingdom of God.
The virtue of temperance disposes us to avoid every kind of excess: the abuse of food, alcohol, tobacco, or medicine. Those incur grave guilt who, by drunkenness or a love of speed, endanger their own and others' safety on the road, at sea, or in the air. CCC 2290