I was thinking a few days ago that many of the friendship lessons are compatible with the gospel. So I'm starting this thread so I and other members can put our thoughts on this topic.
First up Starlight Glimmer's, and Sunset Shimmer's character arcs.
When we first meet Starlight Glimmer she the leader of an equalist cult. Where everypony was denying their talents to find acceptance and friendship. The first apparent problem we see is that equal sign ponies don't actually understand friendship, merely conformity. Then Starlight forces the main six to join and starts programming them and we see the true horror of this cult. It takes away everypony's individuality. Pinkie couldn't make a joke, Rainbow was slow, Rarity was fashion blind, Then via Fluttershy's trick, we find the critical flaw that ends up unraveling the cult, Starlight still has her cutie mark (and apparently needs to cast the spell).
The second time she has a major role we find out she believed that equalist stuff due losing her first friend to him gaining his cutie mark and going off to Celestia's school.
Now in the season 6 opening she adapting to her new life. But her major problem is she can't forgive herself for what she's done (Which I hope will continue to be covered). But because she can't forgive herself she feels she needs to tell Sun Burst and really doesn't want to. She eventually does tell Sun Burst. So currently she confessing her sin but is still holding onto it.

Sunset Shimmer went through a similar arc. When we first met her she was a bully and overall not nice person. She has rapid change of heart at the end of the first movie (in my headcanon this is because she got the My Little Pony version of what happened to Alma the younger, namely having all her sins come to her mind plus in her case showing her true friendship and maybe the results of her actions (I also have the head cannon that human Fluttershy thought about suicide as a result of what Sunset Shimmer was doing to her)). The second movie we see her dealing with what she's done and trying to make friends outside the human 6. By the end of the movie she's forgiven herself and feels she can give friendship advice to her friends. What we see of Sunset Shimmer in the third movie is key because some of the issues she was dealing with in the first movie return (namely her anger issues).

Both of these characters are former villains and unlike Discord, they feel bad about what they have done and are going through the repentance process.