I have not received a response from you from my last post earlier this afternoon. I will go ahead and try to address what the law is in general without that information, but if you want to add the information I asked for, I may be able to provide more guidance. In any event, it is, as you likely already know, unlawful to discriminate against an employee on the basis of their religion. That would be a violation of Title VII of the Civil Rights Act of 1964. There are some limited exceptions that relate to religious organizations but, from what I understand from the few facts I have, you do not work for one of those organizations.
That said, there appear to be two potentially different issues here. One is whether or not you had a legitimate complaint of severe and repeated harassment or adverse employment actions, based on the fact that you no longer attended church regularly. The other is whether or not your employer had a non-discriminatory basis for terminating you or considering you to have quit.
I can't tell you what the ultimate decision of the EEOC or the courts would be in your case, because not only do I not have all of the relevant information from you, I have no input from your employer, which the EEOC and courts would have. I can tell you though that you have a right to file a religious discrimination complaint with the EEOC and you should also sit down with a local employment law attorney to discuss the details of your case to see if they think you should just let the EEOC try to resolve your case or whether they think you should file suit.
Just to clarify the quit/termination issue. If the facts are that the employer was not motivated by your religious situation in determining that you quit (or by terminating you, either one), then it would not be unlawful for them to let you go. In other words, Utah, like most states, is an employment "at will" state. Meaning that an employer can let an employee go for any, or no, reason and with no notice or warning unless the termination would violate an employment contract or is motivated by unlawful discrimination (which I discussed above.) If the facts didn't support either exception, then the employer could let you go for any reason, including a post on Facebook, even if it were unfair. Again, this assumes they didn't let you go because you haven't been going to church.
Please feel free to ask for clarification if needed. If none is needed, then if you could take a moment to leave a positive rating in the box above, I will receive credit for assisting you today. Thank you.