Advice about a friend

I’m not sure if this is the right sub for this, but here I go. I’m not sure what to do my friend at this point, we’ve never had any issues together until today. They grew up in the southern US and went to a private Baptist university (I know but hear me out) while I grew up in the southwest and went to a state school. We both ended up in grad school in STEM. we’ve spent so much time together and they’ve never given me issues about religion whatsoever, claiming they’re agnostic.

Today that changed when they started saying the ‘old testament’ was too judgement heavy compared to the ‘new’ because ‘they’ve read it and took a really good old testament class in college’. And when I would try and open a conversation about it, as we have done many times before, they simply refused to hear my refutations and acted like I just simply didn’t understand. I tried to explain that even the term they were using is offensive but they refused to hear it.

The whole experience has just left me with a bad taste in my mouth and I just had nothing left to explain how offensive they were being. I’ve never had this type of experience with someone I’ve known for so long. Any advice would be helpful of how to deal with this friendship moving forward would be appreciated.