I believe the title already gives a pretty good TLDR, but let me provide a little extra context.
I play in a group with two clerics, a rogue, a fighter and a bard (me). It's also important to know that the DM is a player in one of my groups and plays pretty much exclusively lawful good or neutral good characters. I am on good terms with all of the people involved and I don't intend to change this. We're all adults and if this ever gets out of hand I'm sure we'll find a way to talk things out.
Now to the ingame problem. My character started out chaotic good with a pretty strong emphasis on the chaotic part. She's a fey and orderly things go against her very nature. It's usually small things like planting flowers in the middle of the streets or "resorting" some shop shelves. However, due to some not so nice things going on in the world right now, she began shifting a little more towards the neutral side by developing a indifference towards the lives of several faction members in the world (mostly cultists of various evilish cults).
This led to the party steamrolling a bunch of cultists who expected us to pay a toll for crossing their lands with my character hypnotising them beforehand.
Another encounter had our rogue grow tired of a spectator who blocked our way with obvious implications of combat should we ignore him. Our rogue decided to backstab the spectator mid conversation.
I as a player don't really consider these acts evil. Neither does my character. But apparently the DM and at least one of the clerics see things differently. Which in and of itself is not a problem. However, I got wind that they plan to invoke some sort of plot to "make the party repent for their evil ways". And that's where my issue arises. I have no problem with players or characters who want to be a shining example in an evil world and who see the good in everyone. But I have zero interest in playing such a character and it feels like that is what this amounts to.
So, I'll do the obvious thing and talk to everyone involved before the next session. And that's where you come into play. How would I go about this? What arguments might help my point and what am I missing? If shit hits the fan, I am ok with leaving the game and I know that they will accept my decision. But I prefer to avoid this, as I really enjoy the campaign and my characters role in it and in the group.
Are you and the rogue chaotic good, or chaotic neutral? It doesn’t seem like you’re clear on this with the rest of your party. Murder (e.g., backstab in the middle of dialogue) is not a “good” action, any way you slice it, even if the spectator is an asshole, evil, or through RP, would have eventually led to combat resulting in death anyways. If you were playing true chaotic, it’s understandable, but it doesn’t sound like that is what was made clear.
And if you’re trying to force an alignment shift, consider that you may be ruining the enjoyment of everyone else at the table; if I’m playing a lawful good cleric, I’m not sure my character would party with a true chaotic fey, which would essentially end the campaign.
My fairy is chaotic good, but throughout the campaign had some traumatic experiences that shifted her towards a more chaotic neutral alignment in some regards. I don't know the rogue's alignment, but I would guess somewhere in the chaotic-neutral or true neutral area with tendencies of "kill first, ask questions later".
Tbh, I find your mindset understandable, but highly problematic. Why should the chaotic characters always be understanding of the stick up your ass behaviour of the lawful characters while the lawful characters see it as their god given right to tell everyone else how to behave. Sure, in the real world, these characters would probably just go their separate ways, but this is pen and paper. It's everyone's job to make sure the party sticks together. And that includes the lawful-stupid characters and their players!