I wasn't originally going to enter this, but I got irritated. There's some stuff I would've liked to work out better, but the deadline is approaching, so it'll have to stay like this.
"Think about the theme of good versus evil"
Good and evil designate a moral status, an abstract concept limited to human perception. It is a mechanism of sorts that is what keeps us from destroying ourselves completely. It's rather failing, but anyway. Also, it is unrelated to appearance.
Therefore, in order to depict a conflict between good and evil, both sides would need to display actions that evidence their moral inclination. I went for the simplest : the good side helps people, the bad side doesn't. The versus could not be a battle, because if the sides were battling each other, they would be too busy to show moral attitude. So here, the versus is depicted through the struggle of individuals to free themselves from their own failings.
I consider the idea that morality can be tied to something like appearance, as frequently happens in fiction (villains are dark, sickly, pale, ugly, albino, really smart or really stupid, deformed), to be a form of evil. Just go to any school and see which children are bullied : the different. It encourages the idea that things can be judged on first appearance, and questions don't need to be asked.
Reality doesn't work in black and white standards however, so both sides have light at their core here. Since angels and demons tend to pop up a lot in this contest and I like drawing feathers anyway, I had a look at the bible for usable symbols. The bible uses light and dark mainly as metaphors for wisdom and mental blindness, it never assigns any specific appearance to demons as far as I could tell so I skipped them altogether. In fact, several of the forces of good look what modern day sentiments would describe as "demonic". Fits well, since the right thing to do isn't always the most pleasant.
The symbols here go as follows :
The radiant angel
Inspired by a text in the bible that says the devil will present himself as an angel of light. It can be interpreted as the manifestation of all that is wrong with the human subconscious, with false guidance that promotes blindness, or simply the flock motions of the human race towards its glorious self-destruction.
The gray humanoids
They are not evil. They are not good. They have not enough identity to have defined themselves and may become either depending on influence and situation. They are part of the flock of sameness, only seeing what they want to see. Their brethren suffer, those that are different are excluded. The embryos are their true selves, underdeveloped and their eyes full of light so they cannot see. They are on the heads, positioned to be demonstrated when necessary, yet not really anything alive yet.
Horns and halos
Halos are not mentioned in the bible, they originate in the worship of solar gods, something "heathen" that become "holy". Therefore, they make a good symbol for self-deception and self-righteousness. Horns are a symbol of power in the bible and are not associated specifically with either good or evil, but have become a symbol of evil in the same artistic streams that added halos to Christianity. In this image, horns are used in their original meaning and represent a growing power, they allow the embryos to rise above the halo and see. Or not. Similarly, the lamb has seven horns, representing total power.
The red mass around the sphere
These are growing individuals. They may or may not be good, yet or ever. The sphere they are drooping from under is this world, which are severed from if they don't want you anymore, which it doesn't when you are different. Yet the tendrils of the angel try to keep them back.
The shadowed angels
They represent good, all different from each other yet united. Their side is full of eyes and can see in all directions, and they help whom they can help, open for all, also alert for danger. They represent those who have reached independence and can see, being humans to their fullest nature. The snakes are there to combat the tendrils, chosen because snakes made for the least crowded counter measure than the original plan I had, and they need some positive attention too for a change.
Eyes and Light
Eyes represent the ability to perceive, so the evil side is full of closed eyes. Both sides have light, but the good side has many colors while the evil side only has gray (no colors) for its creations, and instead has a blinding amount of light, while that of the good side has a healthier balance.
The colors don't really have much meaning here, I just chose them cause they're pretty. I originally meant to have no color for the evil side at all, but while messing with some potential fiery glow for the snakes I liked the effect as it crossed the wing, and just went with it.
Real evil doesn't tend to come with a dark cloak and cackling voices. The greatest evils in this world are committed by those who think they are not crossing the line. Those who bully or those who slaughter, they all think they are right in their actions, that it's okay, it's just a game or it's for the greater good. Some simply despair because there seems to be no way out, victims themselves. The lines blur, and gray needs to be acknowledged. Yet we're always learned not to ask questions. Humans generally find it easier to tie everything to simplistic black and white standards, don't care to ask nor little questions, nor large questions.
A man named Elie Wiesel once said : "The opposite of love is not hate, it is indifference."