What is the ruling on consuming foods containing gelatin, monoglycerides, diglycerides, pepsin, and rennet?

Allah has permitted good things for Muslims and forbidden impure things for them, such as carrion, flowing blood, pork, what has been slaughtered for other than Allah, every beast of prey with fangs, every bird of prey with talons, and domestic donkeys.

As for processed foods, gelatin is forbidden if its source is pork or any forbidden animal. Vegetable fats are permissible unless mixed with an impure substance. As for animal fats, if they come from a permissible animal, their ruling is the same as its meat. If they come from a forbidden animal, such as pork fat, then it is forbidden to use them in food.

Cheese made from the milk of a forbidden animal is not permissible to eat. If it is made from the milk of a permissible animal using rennet from a ritually slaughtered animal and is not mixed with any impurity, then it is permissible. However, if it is made from rennet of a dead animal, the preponderant opinion is that it is forbidden. If it is made from pig rennet, it is not to be eaten.

When there is doubt about the permissibility of food, it is preferable to avoid it as a matter of piety, in accordance with the Hadith of Nu'man ibn Bashir: "The lawful is clear and the unlawful is clear, and between them are doubtful matters." The general rule for foods is permissibility unless there is evidence of their prohibition. So, if it is proven that a forbidden ingredient is part of their composition, they must be avoided.