What is meant by making exception in Islam is that a person would add the condition “if Allah wills” when speaking about his own Islam like saying “I am a Muslim if Allah wills.” The majority of Ahlu Al-Sunnah Wal-Jamaa’ah do not allow it when speaking about Islam just like they allow it in Imaan since Islam is not the same as Imaan.  This is because Imaan is of degrees, wherein people are of various levels, while Islam is the least of these levels, and there is nothing beyond it except disbelief.  With that said, whoever is not a Muslim is therefore a disbeliever, however someone who is not a believer (mu’min) may yet be a Muslim, because whoever pronounces the Two Testimonies of Islam becomes a Muslim, and has distinguished themselves from the disbelievers, and so the rulings of Islam are applied to them. The divine texts have indicated the permissibility of saying “I am a Muslim” without adding the condition of saying “if Allah wills”, as is the case when Allah the Exalted says, And who says anything better than the one who supplicates to Allah and does righteous actions and says: “Indeed I am from the Muslims.” Fussilat :33 and The Nomads of Arabs say: “We have believed.” Say “You have not yet believed; rather say you have submitted” al-Hujuraat :14 [180] “al-Imaan; Haqiqatuhu, Khawaarimuhu, Nawaaqidhuhu, ‘ind Ahl as-Sunnah” – ‘Abdullah al-Atharee (p.109) . Ibn Taymiyyah commented on the ayah by saying: “This ayah is from what Ahmad ibn Hanbal and other than him used to prove that you may make exception in Imaan but not in Islam, and that the people who commit major sins leave the levels of Imaan but remain upon Islam. Al-Maymoonee said, “I asked Ahmad ibn Hanbal about his opinion regarding saying “I am a believer if Allah wills” to which he said, “I say, I am a believer if Allah wills, and I say, I am a Muslim without making exception.” I said to Ahmad, “Do you distinguish between Islam and Imaan?” to which he said to me, “Yes” so I said to him, “By what evidence do you support that?” He said to me, The Nomads of Arabs say: “We have believed.” Say “You have not yet believed, rather say you have submitted” al-Hujuraat :14” [181] Reported by al-Khallaal in “as-Sunnah” (3/604) ” [182] “Majmoo’ al-Fataawa” (7/253) So whoever pronounces the Two Testimonies of Islam then they are a Muslim; they are due whatever the Muslims are due, and upon them is whatever is upon them. Every one of them may describe themselves as such without making exception. Ibn Taymiyyah said, “The preponderant position of the people of hadeeth is that there are no exceptions to be made in Islam, and that is what is well-known from Ahmad, may Allah be pleased with him.” [183] “Majmoo’ al-Fataawa” (13/43) And he also said, “Ahmad refused that there are exceptions in it i.e., Islam according to the opinion of az-Zuhree that it Islam is the statement Two Testimonies of Islam. That is what has been transmitted by al-Athram and al-Maymoonee and other than them. As for his other answer when he does not go according to the opinion that Islam is the statement, thus adding the condition of saying “if Allah wills” can be made in Islam as they can be made in Imaan, then that is because a person cannot definitely declare that they have done every act that they have been commanded with in Islam… so if what is meant by Islam is the statement then in that there are no exceptions to be made, as has been reported from Ahmad and other than him. And if what is meant by it is the carrying out of all apparent and outwardly obligations, then making exceptions in that is like making exceptions in Imaan. And since whoever comes with the Two Testimonies of Islam becomes a Muslim, distinguished from the Jews and the Christians, and the rulings of Islam that apply to the Muslims apply to them, then that is what someone may definitely declare about themselves.” [184] “Majmoo’ al-Fataawa” (7/415)