Is denying the stoning of the married fornicator considered a denial of what is known by necessity to be part of the religion?

The jurists of the Ummah have unanimously agreed on the punishment of stoning (rajm) for the married fornicator. The Khawarij and some of the Mu'tazila dissented from this. This consensus is not considered a matter "known by necessity" in religion, so whoever denies it does not become an infidel unless proof is established against them and the matter becomes clear to them. However, such a person is considered misguided and an innovator of a great heresy.

Adultery itself is known by necessity to be forbidden, and the punishment of lashing for the unmarried fornicator is mentioned in a Quranic verse. Whoever denies it after proof has been established against them commits an act of disbelief.

As for stoning, despite the consensus on it, it is not considered a matter "known by necessity." Its denier is not denying a Quranic verse. Umar ibn al-Khattab warned against denying stoning, and Ibn al-Jawzi and Ibn Hajar considered the abandonment of the consensus on the continuation of the ruling of stoning to be misguidance.

Umar ibn Abd al-Aziz's statement regarding those who deny stoning, "They have disbelieved in Allah and His Messenger," is to be understood as a lesser form of disbelief (kufr duna kufr) that does not expel one from the fold of Islam, as it has not been narrated that he ruled them to be apostates.