Has Islam fully differentiated between halal and haram. What is the nature of the concept of halal in Islam. How can I explain this concept to a non-Muslim?
I believe you want to confirm if Islam has clearly demarcated between halal and haram. How do we define the concept of halal? We believe that Islam has not defined all halal and haram acts. Islam relies on the guidance provided to mankind through fitrah (human orientation). We know that every man approves kindness and fairness and disapproves oppression and cheating. Similarly falsehood is universally condemned and truthfulness is praised as worthy. There are a multitude of such concepts which man knows without experience.
Then there are previous revelations. The Prophets of God have always taught what God wants us to do. They forbade the evil and the unallowable. The practices and examples of the Prophets therefore provide a great source of knowledge in this regard.
The Islamic Shari'ah has mostly referred to the acts as allowable and forbidden taking them for granted. It refers to the established concepts. There are only a few things upon which humans could err and where there was a difference of opinion. It is these debateable issues where Islam has pronounced judgment. The question of eating pork, consuming flesh of dead animals and devouring interest are examples.