The stretch is yours with Satanists invoking curses on the food you eat. Why is it not possible for a Satanist somewhere on earth to invoke Satan and curse all the grass fed meat in the world. Should we worry about it? How would it affect the grass fed beef in any way?
Or maybe Aliens from the planet Alderone ..Could happen.
I gave an extreme example to illustrate the dilemma..You took things even further not to clarify but to confound. You would rather detour the conversation to the nature of the example than deal with the actual question.
Here is the question once again. If someone from a Pagan or Muslim religion "Blessed" your food, would you be comfortable still eating it?
I think that is a judgement call. You seem not to be concerned. Thanks for your vote.
If some amorphous ill defined evil person put a general curse on all the foods I prefer to eat ( like grass fed beef) I probably would not care.
If I went to a Halal butcher who blessed the very food I was about to eat, I would care and pay some attention to the situation. My Priest has mentioned in passing not to eat Halal meat, so I am pretty sure there is a divided opinion among Orthodox concerning food "Blessed" by Muslims. I would expect that food offered on a Hindu Altar, like what the Hare Krishna's serve, would be strictly off limits.
That's my vote
Then listen to what your priest says. It's a pastoral issue, not a dogmatic one. Worry about what comes out of your mouth rather than what goes in. Your extreme examples are just that...extreme. Realistically, if I knew someone place a curse on food I was about to purchase, no big deal, I wouldn't purchase it. If I unknowingly consume food that has been "cursed," I trust God will protect me. If not, then that is His will. I've eaten at Turkish restarants, eaten halal chicken and beef, and have been in Muslim households. In the last example, I was served halal food and I ate it. It would have been an insult and an affront to the hospitality provided to me to refuse because maybe prayers to Allah were made during the preparation of the food.
A different example, I was in a Vietnamese household. Traditionally, food and incense is placed before the statue of Buddha. In this case, I would not eat of that food, because it was offered specifically for the Buddha as an offering. Which goes back to my example of Daniel in the Bible. There's a difference in what you are saying and what happens in the daily goings-on in a Muslim butcher shop or restaurant. Even an Indian restaurant.
Do you go to Chinese restaurants? More often than not, there is a Buddha. Do you eat food prepared there? By your logic, you shouldn't.