Is the distinction between matters that are apparent and what is known necessarily to be part of the religion correct, and did any of the Salaf assert it, or is the meaning one and the one who denies it is deemed an apostate even if he was unaware of the ruling?

What is known of the religion by necessity is what is known by both the common Muslims and their elite, and in which knowledge is equal among all. It does not admit doubt, such as the obligation of prayer and fasting, and the prohibition of fornication and alcohol.

As for apparent issues, they are those issues that are explicitly stated and well-known among both the elite and the common people, even if they do not reach the level of what is known by necessity. The one who denies them also commits an act of disbelief (kufr). There are also issues that are agreed upon but are neither apparent nor known by necessity, and the one who denies them does not commit an act of disbelief.

Furthermore, what is known by necessity and apparent issues vary according to different times, places, and people's circumstances. What may be known by necessity in one time or place may not be so in another. The ignorant person who has not received religious knowledge is excused until the prophetic proof is established against them.