No, it would never be considered rude to inquire after the contents of food being offered for your consumption, whether for religious or health reasons, as long as you yourself are not rude in your manner of inquiry.

"I'm personally deeply religious and my faith precludes me eating pork, or consuming any alcohol; may I ask if you were planning on using any of either in the ingredients of the meal?" ... nice, polite, non-confrontational.

"I'm a Muslim and we can't eat port, you Christian wanker! What are you DOING?!" ... not so much. :)

No, it would never be considered rude to inquire after the contents of food being offered for your consumption, whether for religious or health reasons, as long as you yourself are not rude in your manner of inquiry.

"I'm personally deeply religious and my faith precludes me eating pork, or consuming any alcohol; may I ask if you were planning on using any of either in the ingredients of the meal?" ... nice, polite, non-confrontational.

"I'm a Muslim and we can't eat pork, you Christian wanker! What are you DOING?!" ... not so much. :)