Is it permissible to eat meat of a religiously edible animal (e.g., cow) bought from a shop whose owner’s religion is unknown, and thus, there is no way to know that it is slaughtered appropriately or not?
It is not permissible to eat the meat of lawful to eat or muhallal animals without ascertaining that it meets the religious criteria of slaughtering. Hence, if the meat is obtained from a person who is unknown (i.e., to be a Muslim) and it is not possible to ascertain fulfillment of the conditions, then it is not permissible to eat the meat.