Let me illustrate with a few examples.
Examples of good in Christianity:
- Love: it's evident that love feels good and promotes behaviors that make others feel good. Therefore, love ranks very high on the "wellbeing scale".
- Joy: the experience of joy ranks very high on the "wellbeing scale".
- Peace: same thing.
- Self-control: this basically means having the ability to avoid falling into the trap of addictions and compulsive behaviors, which is a great ability to have considering that addictions and compulsive behaviors can cause a lot of suffering to oneself and others. So, again, this virtue promotes wellbeing.
- Faith: it's less obvious how to put this one in terms of wellbeing and suffering, but if we think of faith as "trust", then faith basically means trusting what God is telling you to do, and if we assume that God is omniscient and therefore has an optimal plan that ultimately seeks to maximize wellbeing (heaven) and minimize suffering (hell), then faith in (and obedience to) this kind of God should promote behavior that maximizes wellbeing and minimizes suffering in a holistic manner (i.e., by trusting and obeying God we are cooperating with God's plan and thus contributing to the ultimate maximization of the wellbeing of the whole creation.)
Examples of evil in Christianity:
- Hatred: it's evident that hatred causes a lot of suffering.
- Anger: same thing.
- Envy: it can cause a lot of psychological suffering to the envious person, and the envied person may suffer as well if the envious person decides to do something stupid against them.
- Stealing: very obvious, victims of stealing can experience a lot of suffering.
- Lying: this one can be a bit trickier, since there might be situations in which lying can actually promote wellbeing, e.g. lying to the Nazis to save a Jewish family that is hiding in your basement. But there are plenty of cases when lying can cause suffering, for example when misinformation is propagated, causing people to make wrong decisions based on false information.
- Fornication and Lust: this one is even trickier. Sexual desire and sexual pleasure feel good, so in this sense they have positive points on the "wellbeing scale". Perhaps someone might say that fornication might lead to STDs, but if proper safety and hygiene measures are taken, this potential risk can be greatly mitigated, so not a compelling argument in my opinion. Perhaps a better argument could be that lust might lead to pernicious behaviors such as sexual harassment and even rape, and these can undoubtedly cause a lot of suffering to the victims, and so we can trace an indirect path from lust to these harmful behaviors. But again, people can be lustful in private, using their imaginations, porn, etc. Not everyone who has lustful desires is a rapist or a sexual harasser, so this argument would not apply to those cases. Maybe a better reason why lust is seen as wrong is because the level of wellbeing it produces is of "lower quality" than the wellbeing experienced by someone "full of love". In other words, "love" is of a higher quality than "lust", meaning that love ranks higher than lust on the "wellbeing scale", and therefore love should be preferred. But this would only make sense if love and lust are mutually exclusive (otherwise, you could enjoy both love and lust at the same time and have the best of both worlds). Another possible reason against lust and fornication could be that they can lead to compulsive behaviors and obsessions, which may impair a person's ability to behave in loving ways, be productive and useful to society, etc., which can be similarly argued against other compulsions such as alcohol addiction, drug addiction, gambling, etc.
Are good and evil in Christianity ultimately based on maximizing wellbeing and minimizing suffering?
Extra comments on homosexuality:
The issue of homosexuality seems to be a good objection and potential counterexample to the view of morality as based on maximization of wellbeing and minimization of suffering that I'm defending here. How is wellbeing increased and suffering decreased by forbidding homosexuality? However, I still think there is a way to frame the prohibition of homosexuality in Christianity in terms of wellbeing and suffering, as follows:
- If homosexuality is a sin that can get one sent to hell (maximum suffering) instead of heaven (maximum wellbeing), then it should be in one's best interest to refrain from homosexuality.
- Homosexuality is a behavior that doesn't align with God's original plan for humanity. So we could say that God envisioned an optimal plan for humanity, and allowing homosexuality in would make things suboptimal from God's perspective. And maybe the reason has to do with reproduction and other considerations, fewer salvations, and therefore less people enjoying the maximum wellbeing of heaven, I don't know.
- We could also include God's wellbeing into the equation. As far as I understand, whenever someone sins against God, that makes God angry and/or sad in some sense. Therefore, in order to maximize God's wellbeing, humans should avoid sinning, which includes homosexuality.