Evil is just shorthand. An evil is in fact a collection of many evils.
The shorthand is manipulative. It leads to us over-simplifying. The would-be heroes want us to do that for their own glory and ends.
On the other hand, if we talk about evils a new problem arises. The picture gets too big to discern accurately.
Either way, we end up using words to let evil in. Evil grows where the diagnosis is faulty.
So back to talking about evils.
So if it is evils what if it they are myriad collections of two kinds of evil?
Some say evil is a real substance - maybe even an intelligence. Others say it is a mere lack of good and is nothing in its own right. The idea is that good alone is real and evil is the distortion of it - a metaphorical parasite. Some say both are true.
It is possible that if substantial evil exists that maybe the merely parasitic version exists too.
Evil will never really be untangled if it is a mixture of powers and lacks - it will be the head of a Hydra. Cut it off and another one grows in a new form. Note too that if evil is a power then it is a mystery. The lack vision is also riddled with mystery. It is like there is space there that bad things are coming from. It feels thin and too abstract. It does not match the experience of hideous depression, for example.
We do not know what we are talking about enough to boldly say that evil leads to good. Just because good follows evil does not mean the evil led to it. Evils compete with each other so it can look like evil makes some good possible. The Church says that Satan luring you into homosexuality does not mean he will not mock you for it in Hell. He could be a gay-basher. People want the evils that suit them. It does not mean they agree with every evil. They are still evil.
If you are evil, part of it is telling yourself that you are aiming for good.
FINE-TUNING
No matter how hard humans try to defend the lack teaching, they do respond to evil as if the evil is a real intelligent higher power.
The lack doctrine suggests that the more evil you are the less you exist - that makes no sense and does not relate to our experience either.
Religion assumes that things such as the emergence of life in our universe is so improbable that only a good and intelligent God could be responsible. Then why did he make us see evil the way we do as real? He acts as if he couldn't make substantial evil and had to do the next best thing. He makes evil as good as real in that way and engineers us to respond to evil as if it is. Or did he make substantial evil? This would point to intelligence that collapsed. Or a God who is both smart and stupid. More likely it tells us that no matter how much it seems that intelligence is behind all things, it is not.
LIKE LEADS TO LIKE
If substantial evil does not exist, it seems that does not mean evil is impossible. We suppose that evil happens and it would be parasitical evil. And that you can increase in that evil.
What if some evil is substantial and the rest of evil is parasitic, a mere lack? We will not tell them apart exactly anyway. But also substantial evil will not want us to and will prevent us.
Substantial evil would lead to other kinds of substantial evil. The lack of clarity will help that to happen.
And parasitic evil would lead to substantial as well.
Distinguishing them would be impossible for substantial evil can look like parasitic evil and it would be safe to assume it is there. Take the safe side.
We find that the parasitical evil notion should be irrelevant in daily life. If we treat evil as substantial, we have to live with how difficult that is going to make our lives. Moralists say that morality can be terrible but we still have to practice it for the alternative is worse.
If we do not know if evil is substantial or parasitic, we have to treat it as if it is substantial.