What is the difference between fiṭrah, millah, and dīn? May Allah reward you.

In language, fitra (primordial nature) means creation, and in the texts, it signifies the innate predisposition that Allah has instilled in humans, making them receptive to accepting the divine law. This is as stated in His saying, the Most High: “The fitra of Allah upon which He has created mankind” (Quran 30:30), and the Prophet, peace and blessings be upon him, said: “Every child is born upon the fitra.”

As for milla (creed/religion), it is the religion, whether it be true or false, as in the saying of Yusuf (Joseph), peace be upon him: “Indeed, I have abandoned the religion of a people who do not believe in Allah” (Quran 12:37). Milla refers to the divine law and religion, and it is applied to Islam, Christianity, and Judaism.

The difference between them is that milla is only attributed to a prophet and is not attributed to Allah the Most High or to individual members of the nation. It is used to refer to a set of divine laws, not individual ones.