When speaking about contrast, the most used example is light and darkness. We seem to compare every opposing situation to some variation of light and dark, such as night and day. Likely because it is so easily seen and understood. What I love about it, is that it helps, even allows us to see the difference, that there is a contrast.
Especially in a religious context, I’ve been told that the contrast is good. Experiencing darkness allows you to better appreciate the light. The same goes for good and bad, enjoyment and suffering, as well as countless other comparisons. One of my favorite little parables was about a tapestry complaining to the weaver about having so much dark threads woven in, rather than being full of bright colors like the other tapestries. These dark threads representing trials and hardships in life. When the tapestry was finished, it realized that it was absolutely stunning because the dark threads allowed the few gold threads to stand out.
Contrasting is a tool used to accentuate the differences, but also the goodness and specific qualities of each aspect. This is true with diversity in people, and in themes in stories. Contrasting is a helpful writing tool that allows a writer to highlight pros and cons of different concepts. Jane Austin uses it in Sense and Sensibility with two sisters having completely opposing belief systems. I’ve seen it in Les Miserables by Victor Hugo in the differences between Jean Valjean’s way of doing business compared to that of the Thenardiers.
I love to use contrast when expressing themes in my stories, because it is a way that I can show and not tell the preferred stand point of the theme. You already see it in the good vs. evil. You can use this in more than just the relationship between the antagonist and protagonist, I like to use it in the character arc, showing how a character has changed by highlighting the contrast of their responses in a similar situation from the beginning when in the end.
Look at the contrasts you can find and think about what they point out to you. Use the contrasting tool in your writing or brainstorming to help you more clearly articulate a change or statement. Enjoy your contrasts!