Question

What is the ruling on one who wants to become Muslim, and knows that there is a Messenger to humanity, and believes in him, but he does not know his name? Has he become Muslim, or must he first know the name of the Messenger? Is it acceptable for him to know [the Prophet’s] kunyah, or a name other than Muhammad, such as Ahmad or al-Maahi?

Answer

Praise be to Allah.

Firstly:

No one becomes Muslim until he utters the Shahaadatayn (the twin declaration of faith), if he is able to utter it, or affirms its meaning. An-Nawawi (may Allah have mercy on him) said:

Ahl as-Sunnah – the scholars of hadith, the fuqaha’ and the scholars of kalaam – are agreed that the believer who is deemed to be among the “people of the qiblah” [i.e., Muslims] and will not abide forever in Hell can only be the one who believes in his heart in the religion of Islam with certainty and free of any doubts, and utters the Shahaadatayn (the twin declaration of faith). Whoever omits either part of it is not one of the people of the qiblah at all, unless he is unable to utter it because of a speech defect, or because he was not able to utter it before death overtook him suddenly, or for some other reason, in which case he is indeed a believer.

End quote from Sharh an-Nawawi ‘ala Muslim (1/149).

Shaykh Ibn Baaz (may Allah have mercy on him) said:

It is essential to utter the Shahaadatayn; if he is able to utter them but does not do so, then he had not entered Islam until he does utter the Shahaadatayn. This is a matter on which there is scholarly consensus. Moreover, along with uttering the words, it is essential to believe and affirm the meaning of the Shahaadatayn.

End quote from Majmoo‘ Fataawa Ibn Baaz (5/340).

If he is not able to utter these words, such as one who is nonverbal, then his becoming Muslim is done by writing, if he is able to write, or by making gestures or signs which indicate that he has truly become Muslim and has accepted Islam willingly.

See the answer to question no. 224858.

Secondly:

It is obligatory to mention in the Shahaadah (testimony of faith) the name of the Prophet Muhammad (blessings and peace of Allah be upon him); all his names and his kunyah are equal in that regard, such as Muhammad, Ahmad, al-Maahi, Abu’l-Qaasim, and so on.

Al-Haleemi (may Allah have mercy on him) said:

If a disbeliever says: “Laa ilaaha illa Allah, Ahmad rasool-Allah [There is no god but Allah, Ahmad is the Messenger of Allah]”, that is the same as saying “Muhammad rasool-Allah [Muhammad is the Messenger of Allah].” Allah, may He be glorified and exalted, says (interpretation of the meaning): “…and bringing good tidings of a messenger to come after me, whose name is Ahmad” [as-Saff 61:6]. The meaning of the two names is the same.

So there is no difference between Ahmad and Muhammad.

If he says: “Abu’l-Qaasim rasool-Allah [Abu’l-Qaasim is the Messenger of Allah],” the same applies. And Allah knows best.