It is essential for everyone to have îmân; îmân is necessary for everybody. Those who have îmân should carry out the fards and abstain from the harâms. Every Mu’min (Believer) is obliged to carry out the fards and abstain from the harâms, that is, to be a Muslim. Every Mu’min loves our Prophet (sall-Allâhu ’alaihi wa sallam) more than his own life and property. A symptom of this love is to carry out the sunnat and abstain from the makrûh. After following all of these, the more a Muslim adapts himself to him in what is mubâh, the more perfect and the more mature will he become. He will become all the closer and more beloved to Allahu ta’âlâ.
It is called Îmân to like and to admit sincerely, that is, to believe, all of what Rasûlullah (sall-Allâhu ’alaihi wa sallam) said. Those who believe so are called Mu’min. It is called Kufr not to believe even one piece of what he said, and to doubt if it is good and correct. People who disbelieve so are called Kâfir. Things which Allahu ta’âlâ clearly commands in the Qur’ân al-kerîm are called Fard. Things which He clearly forbids and prohibits by saying “don’t” are called Harâm. Things which Allahu ta’âlâ doesn’t clearly command but which are acts our Prophet praised or which he habitually did or which he did not prohibit, though seeing them done, are called Sunnat. It is kufr (disbelief) to dislike the sunnat. It is not a sin not to do them, as long as you like them. Those things which are not liked by him, and which also eradicate the blessings of worships are called Makrûh. The things which are neither commanded nor prohibited are called Mubâh. All these commands and prohibitions are called Sharî’at or Af’âl-i mukallafîn or Ahkâm-i Islâmiyya.
Af’âl-i mukallafîn consists of eight aspects: Fard, wâjib, sunnat, mustahab, mubâh, harâm, makrûh, mufsid. Things that are not prohibited, or though prohibited, their prohibition has been abolished through one of the reasons which the Sharî’at accepts as an excuse, a hindrance or a necessity, are called Halâl. All mubahs are halâl. For example, it is halâl to lie in order to reconcile two Muslims. Everything that is halâl may not be mubâh. For example, it is not mubâh, but it is makrûh to go shopping while the adhân is being called. Nevertheless, it is halâl. A Muslim crier calls Muslims to pray when it is prayer time; this public announcement is called the adhân.
It is fard to learn and know the tenets of îmân, and the various fards and harâms. Thirty-three fards are well-known. Four of them are basic; to perform namâz, to fast, to give zakât, and to perform hadj (pilgrimage). These four fards together with îmân are the basis of Islâm. He who has îmân and who worships, that is, he who carries out these four fards is called a Muslim or Muslimân. He who carries out all four of them and abstains from the harâm is a complete Muslim. If one of these is defective or nonexistent, his state of being a Muslim will also be defective. He who does not carry out any of them may be a Mu’min (believer), but he is not a true Muslim. Though such an îmân protects one in this world only, it is difficult to transmigrate to the Hereafter in possession of this kind of îmân. Îmân is like a candle. Ahkâm-i İslâmiyya is like the lantern, the glass globe around the burning candle. The candle and the lantern which contains it represent Islâm and Dîn-i Islâm. The candle without the lantern will go out quickly. Islâm cannot exist without îmân. Therefore, where there is no Islâm, there is no îmân, either.
Dîn (religion) means the way prescribed by Allahu ta’âlâ in order to guide people to endless bliss. The unwholesome ways which people make up under the name of religion are not called religion; they are called irreligiousness and disbelief. Since the time of Hadrat Âdam, Allahu ta’âlâ has sent mankind a religion by means of a prophet every thousand years. These prophets (salawatullahi ta’âlâ ’alaihim ajma’în) are called Rasûl. On the other hand, in every century, by making the purest person the prophet, He has strengthened the religion through him. These prophets who followed the rasûls are called Nabî. All the prophets have communicated the same îmân; they have asked their ummat to believe in the same things. Yet, since their Sharî’ats, that is, the things that are to be done and avoided through the heart and body, were different, their being Muslims was different.
He who has îmân and adapts himself to the Sharî’at is a Muslim. Those who want to adapt the Sharî’at to their desires and pleasures are disbelievers. They don’t understand that Allahu ta’âlâ has sent down the Sharî’at in order to break the desires and pleasures of the nafs and to prevent their excessive indulgence.
To have îmân means to begin following him (Rasûlullah) and to enter into the door of happiness. Allahu ta’âlâ sent him to invite all the people of the world to happiness and declared in the twenty-eighth ayat of Sûrat-us-Saba’: “O my beloved Prophet! (sall-Allâhu ’alaihi wa sallam) I send you to humanity so that you should give the good news of the endless bliss to all the people in the world and to guide them toward this way to happiness.”
The first thing necessary for all people is to have îmân and the creed of the Ahl-i sunnat scholars as communicated in their books. It is these scholars who have explained the way of our Prophet Hadrat Muhammad ‘alaihis-salâm’, who have comprehended murâd-ı ilâhî (the divine purpose) of the Qur’ân al-kerîm, and who have extracted the Prophet’s purpose from the hadîth-i-sherîfs. It is the way shown by them that will save us on the Day of Resurrection. It is the Ahl-i sunnat scholars who have transferred the way of Allah’s Prophet and his companions (radî-Allâhu ta’âlâ ’anhum ajma’în) into books and who have protected them against being changed or defiled.
Allahu ta’âlâ declares that disbelievers are His and His Prophet’s (sall-Allâhu ’alaihi wa sallam) enemies. To love the enemies of Allahu ta’âlâ and to cooperate with them draws one towards being hostile against Allahu ta’âlâ and His Prophet. A person thinks of himself as a Muslim, expresses the word tawhîd, and says, “I believe,” and performs namâz and every kind of worship, but, on the other hand, cooperates with disbelievers. Yet he does not know that these loathsome actions of his will extirpate his being a Muslim and his îmân.
For adapting oneself to Muhammad ‘alaihis-salâtu wa-s-salâm’ completely and flawlessly, one needs to love him completely and without defect. The symptom of complete and perfect love is to bear hostility against his enemies, and to dislike those who dislike him. Love cannot include sloth. Lovers, being crazy about their darlings, cannot do anything against them. They cannot come to a mutual agreement with those who act against them. The love for two opposites cannot settle in the same heart together. To love one of two opposites entails enmity towards the other.
Therefore the symptom of existence of îmân in one person is to love Allahu ta’âlâ, His Prophet’s (sall-Allâhu ’alaihi wa sallam) and his muslim brothers. The one says I am muslim, but he loves enemies of Allahu ta’âlâ and His Prophet’s (sall-Allâhu ’alaihi wa sallam) is a big liar, his îmân is absolutely imperfect.
 Ref: This paragraphes are quoted from the book “Endless Bliss” first fascicle page 24, which is the translation of the book “Tam İlmihal Seâdet-i Ebediye” written by Hüseyn Hilmi Işık ‘rahimahullâhu ta’âlâ,’ who passed away in 1422 A.H (2001 A.D.) in Istanbul / Turkey. The book “Tam İlmihal Seâdet-i Ebediye” and “Endless Bliss” published by Hakikat Kitabevi, Istanbul. You can find the whole book and the other valuable books in the web site www.hakikatkitabevi.com.tr and download in PDF format for Adobe Acrobat Reader, EPUB format for iPhone-iPad-Mac devices and MOBI format for Amazon Kindle device.