1- A believer who is Salih (pious, good). He says that he is a Muslim. He holds the belief of Ahl as-sunnat. A person who holds the belief of Ahl as-sunnat is called Sunni (Sunnite). He adapts himself to one of the four Madhhabs of the Ahl as-sunnat. Thus in everything he does he is in a state of obedience to the Shariat. He performs his worships in accordance with his Madhhab. He avoids harams (acts forbidden by Islam). If he makes an inadvertent mistake in this respect, he makes tawba by observing its conditions. Before sending his children to elementary school, he sends them to a Salih imam or to a teacher of Qur'an al-karim. He strives for their learning how to read Qur'an al-karim, memorizing the suras of Qur'an to be recited in the namaz, and learning Ilmihal. He sends them to elementary school after they have learned these things. He sends his sons to high school, to a university for education. It is a must that they learn religious knowledge and begin performing daily prayers of namaz regularly before elementary schooling. A father who does not bring up his children accordingly cannot be a Salih Muslim. He and his children will go to Hell. The worships he has done, e.g. pilgrimages, will not save him from going to Hell. The Muslim who is Salih will never enter Hell.
2- A believer who is Aberrant. He says he is a Muslim, and he is a Muslim, too. Yet he is not Sunni. He is without a Madhhab. In other words, his belief does not agree with the belief taught by scholars of Ahl-sunnat. Therefore none of his worships will be accepted. He will not escape Hell. If he does not perform the worships and commits harams, he will remain in Hell additionally for these sins. Because his aberrant belief does not cause unbelief, he will not remain eternally in Hell. An example of such people is the Shiite group called Imamiyya.
3- The Sinful believer says he is a Muslim, and he is so. He is Sunni, too. That is, he holds the belief of Ahl as-sunnat. Yet he neglects some or all of the worships. He commits harams. The sinful believer will suffer Hell fire if he does not make tawba or attain Shafaat (intercession of the Prophet, one of the Awliya, or Salih Muslim) or forgiveness of Allahu ta'ala. Yet even in this case he will not remain in Hell eternally.
4- A disbeliever from birth is a person with parents who are (or were) disbelievers. He has been brought up as a disbeliever. He does not believe in the fact that Muhammad 'alaihi-salam' is the Prophet. Jews and Christians are disbelievers with (heavenly) books. Communists and freemasons are disbelievers without a book. They do not believe in rising after death, either. People who worship idols and icons are called Mushrik (polytheist). Disbelievers will go to Hell and will be subjected to eternal fire. None of the goodness they have done in the world will be of any use, nor will they save them from Hell. If a disbeliever becomes a Muslim before death, he will be pardoned and will become a Salih Muslim.
5- A Murtad (renegade) is a person who abandons Islam and becomes a disbeliever. All the worships and pious acts he did as a Muslim will be deleted and, therefore, will be of no value after death. If he becomes a Muslim again, he will be pardoned and will become an extremely pure believer.
6- A Munafiq says that he is a Muslim. Yet he is not a Muslim. He is in another religion. He is a disbeliever. He pretends to be a Muslim in order to deceive Muslims. A munafiq is worse than an (undisguised) disbeliever. He is more harmful to Muslims. Formerly, the number of munafiqs was rather great. There are next to none today.
7- A Zindiq also says that he is a Muslim. Yet he is not a member of any religion. He does not believe in rising after death. He is an insidious disbeliever. In order to mislead Muslims out of Islam and to demolish their religion from within, he presents his disbelief in the name of Islam. Qadiyanis, Bahais and Baktashis are in this group.
8- A Mulhid also claims to be a Muslim and thinks he is a Muslim. He performs Islam's worships and avoids the harams. Yet he has greatly digressed from the belief held by the Sunnites in his interpretation of Qur'an al-karim, to the extent that some beliefs he holds abrogates his iman and causes disbelief. In this group are Nusayris and Ismailis, two Shiite sects, and Wahhabis. They try to present themselves as believers and the Sunnis, who are actually people with correct belief, as disbelievers. Since a person who calls a believer a disbeliever will become a disbeliever himself, these people are worse and more harmful to Muslims than disbelievers are.
Any wise person would like to live in comfort and peace in the world and to avoid torment and attain infinite blessings in the Hereafter. To this end, I wrote my book Se'adet-i Ebediyye (Endless Bliss). I tried to show the way leading to happiness for all kinds of people all over the world. First, I endeavored to learn it myself. For many years I read hundreds of books. I carried out very stringent research in history and Tasawwuf. I meditated deeply on scientific knowledge. I recognized very well and definitely believed that attaining comfort in the world and eternal blessings in the Hereafter requires being a Salih Muslim. And being a Salih Muslim, in its turn, requires learning the Islamic teachings from books written by scholars of the Ahl as sunnat.. An ignorant person cannot even be a Muslim, let alone be a Salih one. I explained in detail in my book ‘Se'adet-i Ebediyye’[Endless Bliss] how a Salih Muslim should be.