Firstly, we must distinguish between two matters: legal judgment (rulings in worldly affairs) and religious judgment (rulings with regards to faith).
The difference is that a certain matter may be established in legal judgment, meaning it is recognized and applicable in worldly matters, while it may not be established in religious judgment, meaning it is not considered valid by Allah. Conversely, a matter may be recognized in religious judgment, considered valid by Allah, while it may not have a legal application in worldly affairs.
An example of this is when a person pronounces three divorces (talaq) at once but later denies having done so three times. There is no evidence or proof for the three divorces except for the person’s statement. In legal judgment (in worldly affairs), the ruling will be based on his statement, and thus his wife will not be considered divorced three times (meaning she can return to him after the first or second pronouncement). However, in religious judgment (in the sight of Allah), the person is lying, and his wife will be considered divorced three times (meaning the divorce will be considered final and irreversible).
In our interactions with people, we are governed by the rule of legal judgment (not referring to the judgment of a judge, but rather what can be established by evidence or indication).
Secondly, the default principle regarding conversion to Islam is that it occurs in both legal judgment and religious judgment simultaneously. So, whoever legally declares their Islam but does not truly embrace it in their heart (religious judgment), they are considered a Muslim outwardly but a hypocrite inwardly. This means that they will be treated as a Muslim in worldly matters, but Allah will judge their true intentions and actions in the Hereafter.
And whoever declares their Islam only in religious judgment, the default principle is to treat them according to their outward appearance, meaning they are treated as non-Muslims, until their Islam is established through legal judgment. There is no way for us to know what lies between them and Allah. Therefore, they cannot marry our daughters, inherit or be inherited from, and cannot be buried in the graveyards of Muslims, along with other worldly matters, even though they may be among the people of Paradise in the Hereafter.
The evidence for this is that the Prophet Muhammad (peace be upon him) did not declare Abdullah ibn Abi Ibn Salul and his followers as disbelievers, as their judgment was governed by the legal judgment applicable to Muslims, until the Quran was revealed and exposed their true intentions. Similarly, it is reported that Ibn Abbas said: “A man from the Banu Salim passed by a group of the Prophet’s companions while he was driving his sheep. He greeted them, but they said: “He only greeted us to take precaution against us” and killed him. They brought his sheep to the Prophet (peace be upon him), and then the following verse was revealed: ‘O you who have believed, when you go forth [to fight] in the cause of Allah, investigate; and do not say to one who gives you [a greeting of] peace, “You are not a believer,” aspiring for the goods of worldly life’ (An-Nisa’, 4:94). Thus, he was judged to be a Muslim legally.”
Likewise, what Al-Bukhari narrated in his Sahih from Usama bin Zaid (may Allah be pleased with him) who said: “The Messenger of Allah (peace be upon him) sent us to Al-Huraqat, a tribe of Juhaynah. We attacked them at dawn and defeated them. I and a man from the Ansar caught hold of a man of theirs. When we overcame him, he said, ‘La ilaha illallah (there is no god but Allah).’ The Ansari refrained from killing him, but I stabbed him with my spear until he died. When we returned, this news reached the Prophet (peace be upon him). He said to me, ‘O Usama, did you kill him after he had said La ilaha illallah?’ I said, ‘O Messenger of Allah, he said it out of fear of our weapons.’ The Prophet (peace be upon him) asked repeatedly, ‘Did you kill him after he had said La ilaha illallah?’ I wished that I had embraced Islam only that day.”
Accordingly, when a man declares the two testimonies of faith (Shahada), he enters Islam in the legal sense, and the rulings of Islam apply to him. Thus, his marriage contract with the woman is valid based on this status, and what comes after the contract does not affect its validity. We judge based on the present condition, not on future possibilities. Therefore, the marriage contract is valid in terms of legal judgment, while his sincerity and true faith are known to Allah.
However, if he later deviates from some Islamic practices or rituals, this is a subsequent matter that does not affect the validity of the marriage contract, but it may have implications on the continuity of the marriage itself.
And Allah knows best.
Fatwa by Dr. Khālid Naṣr