Raquel, I sympathize with you. This is very difficult, in our parish of all places, we want to feel welcome, open and friendly to all, including the priest. However, what is the worst that can happen, the priest hates you? Won’t let you sing in the music ministry or lector or something? Awkward yes, unfair certainly, but hold your head high and GO TO MASS and realize JESUS WELCOMES YOU THERE.
In one parish I have so antagonized the priest, I know he dreads my walking up to him after Mass to say hello. Sometimes I wear a chapel veil, and that visibly annoys him like crazy. But I have it a bit easier than you that this is not my regular parish, it’s a nearby one I sometimes have to attend due to timing. But I share with you to let you know I just let this go like water off a duck’s back. Also, I am too brash, always take a respectful approach, let your argument speak for itself.
Now, for you, being new and all, how about taking this in steps. Don’t decide whether to send the letter yet, BUT WRITE IT. Get down clearly for your own sake what bothers you, what is right and wrong about what he did. It will be a relief. Maybe others on Catholic blogs can even help you come up with good wording. BE SUPER POLITE and RESPECTFUL (no irony or sarcasm or criticism). Just factually state why you were shocked and disturbed by his comments, why that behaviour seems inappropriate, etc.
OK, now when you have it down, you can decide if you want to mail it, but if you do, you must sign. No anonymous letter is ever taken seriously. Bishops are deluged with them, and priests get them fairly frequently. If it’s anonymous likely the secretary will not even pass along to him.
BUT.....you will have much more confidence if there are like-minded parishioners who would sign with you. Do you know any who feel as you do, and also are holding back, but if you have gone to the effort to compose the letter, they might agree to sign with you. If there is someone you know well enough and who seems orthodox, you could ask their opinion of the letter.
Finally, I hope you decide to send it. IF YOU DO, THE LAST LINE SHOULD BE: “I would appreciate your reply and look forward to receiving it.” This way if the priest ignores you, you have proof you requested communication, you are working at understanding, not a nut just making accusations.
I don’t think you have anything to fear from the letter, it’s hard to say, most priests will not be so vindictive to “punish” you by being rude or excluding you from parish events. But it could happen. But if you’re already in an post, it would be very awkward for him to ask you to leave (for example if you teach CCD), because you’re established and it would show he is prejudiced.
Based on his reply or lack of one, you may want to then forward your letter to the bishop. Not sure who he is, so that may or may not do any good. But start with the priest first, it’s not right to “go over his head” until you give him a chance to address the issue and explain his behaviour. If you are polite, chances are he might be privately annoyed but will realize people in his congregation are smart and he should be more careful with preaching his personal opinion as doctrine (which is unethical). He will know you are right and that alone could make a difference.
It all comes down to can you handle the emotional difficulty of facing him at Mass? I hope you can, it’s no big deal once past the first time, let him be the one to flinch, not you! After all, God is on your side.