Is a person who previously declared that adultery is permissible, then uttered the Two Testimonies believing in the prohibition of adultery, considered a Muslim who will not abide eternally in Hell, or must he verbally or publicly affirm the prohibition of adultery to become a Muslim?

Considering the unlawful as lawful, regarding matters upon which there is a consensus, such as adultery, constitutes disbelief and apostasy, and it carries two rulings:

1. The Apparent Ruling: The Muslim does not return to their religion except by uttering the two Shahadas and explicitly declaring the prohibition of adultery. They must declare the prohibition of adultery in front of whoever heard them declare it lawful, so that the ruling of apostasy is lifted from them outwardly. If they do not do so, their blood and wealth become permissible, marriage to them is forbidden, and no funeral prayer is offered for them if they die.

2. The Inner Ruling: If they utter the two Shahadas, believe in the prohibition of adultery, and their repentance fulfills the five conditions (sincerity, remorse, abandonment of the sin, determination not to return to it, and that the repentance occurs at a time of acceptance), then they return to faith between themselves and Allah.

And Allah knows best.