You are largely on your own in terms of figuring out how to deliver the message. It's highly sensitive to who the people are, what they're like, the degree of power held by HR in your Company, and all sorts of things that we don't really know. The message, however, is simple: if employees start feeling like they're not being included in work-related events because of their religion, they will start seeing that they are being excluded, whether that's true or not. That will eventually end up leading to people talking to state or federal agencies, which can result in a possibly uncomfortable and definitely expensive situation for your Company. It can also mushroom into additional, unintended action when word gets out such as individuals beginning to question why they were not hired (promoted, given a raise, trained, etc). I'm sure you know all this, but figuring out how to package it to leadership in a way that makes them pay heed for the good of the Company without jeopardizing your role with the Company or yoru own job as a newer person showing up (from California, no less!!!) and rocking the boat.
Utah escapes the 9th circuit: it's in the 10th and I don't know a whole lot about the 10th's stance on such matters but federal law is pretty clear.
As you also probably know, Sexual Harassment is merely an extension of sex discrimination. You can have religious harassment as well in the same vein. While most people would not equate quid pro quo sexual harassment with "inviting" someone to their place of worship in order to advance in the Company, they are more alike than not in the eyes of the law and your employer needs to know that.