I'm planning on not attending their Christmas party.
Why aren't you going to attend it?
I do not like their parties and do not see a reason to attend it.
If you want to stay home, you should not feel obligated to go.   Make sure that you communicate that you will be going so that they are not expected you and surprised or offended if you do not go.
I don't care they know where I stand on all this shit.
I get that, it's fine to have your own wants and needs. I would highly recommend you let them know beforehand that you won't be attending, that way it would upset them less.