The Prophet (pbuh) was asked about Imān (faith) so he replied: "To believe in Allah and His angels, His books, His messengers, and the Last Day, and to believe in destiny, along with its pleasant and unpleasant aspects."
The pillars of Imān are acts of worship done by the heart and due upon every Muslim. The Islam of anyone can only be valid if he has these beliefs. Hence, they are called the pillars of Imān. The difference between the pillars of Imān and those of Islam is that the pillars of Islam are outward acts to be done by a person's body parts, like uttering the testimony of faith, performing prayer, and paying Zakah, whereas the pillars of faith are acts done by the heart, such as the belief in Allah and His books and messengers.
The concept and meaning of Imān: It is the heart's firm belief in Allah and His angels, His books, His messengers, the Last Day, and destiny; its pleasant and unpleasant aspects thereof, and following and applying all what the Prophet (pbuh) brought, whether verbally, like saying "there is no god but Allah", reciting the Qur'an and Dhikr, and praising Allah Almighty;
or as outward physical acts, like prayer, Hajj, and fasting, as well as inward acts within the heart, such as love for Allah, fear of Him, reliance upon Him, and sincerity to Him.
Experts define it briefly as: belief by the heart, speech by the tongue, and actions by the body parts, and it increases by good deeds and decreases by sins.
First Pillar: Belief in Allah
Allah Almighty says: {The true believers are those who believe in Allah} [Ch. 24, Verse 62]
The belief in Allah requires the belief in His Oneness of Lordship, His Oneness of Worship, and the uniqueness of His Names and Attributes. This includes the following:
• The belief in the existence of Allah (SWT)
• The belief that Allah is the only Lord, and that He is the Owner, Creator, and Sustainer of everything, Who manages the affairs of everything.
• The belief that Allah is the only God, and that He alone deserves to be worshiped. Acts of worship must be dedicated to Him alone without any partners, such as prayer, supplication, making vows, sacrificial animals, imploring for help and protection, and all other acts of worship.
• The belief in His Names and Attributes that He affirmed for Himself or that His Prophet Muhammad (pbuh) affirmed for Him, and negating what He negated about Himself of Names and Attributes or what His Prophet negated about Him. This includes the belief that His Names and Attributes are the most superior in terms of perfection and beauty, and that {there is nothing like unto Him and He is the All-Hearing the All-Seeing}.
Second Pillar: Belief in the Angels
Allah Almighty says: {All praise be to Allah, the Originator of the heavens and earth, Who made the angels messengers with two, three, or four wings. He increases in creation whatever He wills. Indeed, Allah is Most Capable of all things.} [Ch. 35, Verse 1]
We believe that the angels are part of the unseen realm, and that they are servants of Allah that He created from light, and made them obedient and submissive to Him.
They are a great creation whose numbers and abilities are known to Allah alone. Each of them has names, traits, and duties that Allah assigned to them. One of them is Jibreel (Archangel Gabriel) who is assigned with delivering the revelation from Allah, the Exalted, to His messengers.
Third Pillar: Belief in Divine Scriptures (Books)
Allah Almighty says: {Say [O believers], "We believe in Allah and what has been sent down to us; and what was sent down to Abraham, Ishmael, Isaac, Jacob, and the descendants [of Jacob]; and what was given to Moses and Jesus; and what was given to the prophets from their Lord. We make no distinction between any of them, and to Him we have submitted."} [Ch. 2, Verse 136]
The firm belief that all the divine Scriptures are the word of Allah,
and that they were revealed from Allah to His messengers bearing the clear truth;
and that Allah Almighty, by sending His Prophet Muhammad (pbuh) to all mankind, has abrogated with this law all the previous laws and legislations and rendered the Qur'an dominant over all the previous scriptures, superseding them. Allah Almighty has pledged to preserve the noble Qur'an against any alteration or distortion, saying: {Indeed, it is We who sent down the Qur'an and it is We Who will be its guardian.} [Ch. 15, Verse 9] This is because the Qur'an is the last revelation to mankind, and Muhammad (pubh) is the last messenger, and Islam is the religion that Allah has approved for mankind until the coming of the Hour. Allah says: {Indeed, the religion in the sight of Allah is Islam} [Ch. 3, Verse 19]
The Divine Scriptures that Allah mentioned in the Qur'an are:
The Noble Qur'an: which Allah revealed to His Prophet Muhammad (pbuh).
The Torah: which Allah revealed to His Prophet Moses (pbuh).
The Gospel: which Allah revealed to His Prophet Jesus (pbuh).
The Psalms: which Allah revealed to His Prophet David (pbuh).
The Scrolls of Abraham: which Allah revealed to His Prophet Abraham (pbuh).
Fourth Pillar: Belief in the Messengers
Allah Almighty says: {Indeed, We sent to every community a messenger, [saying], "Worship Allah and shun false gods."} [Ch. 16, Verse 36]
The firm belief that Allah Almighty sent a messenger to every nation calling them to worship Allah, alone with no partner, and to disbelieve in anything worshiped apart from Him.
And the belief that all of them were humans, men, and servants of Allah, and that they were truthful, trustworthy, and honest, and came with guidance for people; and that Allah supported them with miracles proving their truthfulness, that they conveyed all the message entrusted to them, and that they were all upon the truth and clear guidance.
The call of all of them was the same with regard to the core of the religion, which is to worship Allah Almighty alone and not associate anything with Him.
Fifth Pillar: Belief in the Day of Judgment.
Allah also says: {Allah - there is no deity except Him. He will surely gather you all for [account on] the Day of Resurrection, about which there is no doubt. Who is more truthful than Allah in speech?} [Ch. 4, Verse 87]
The firm belief in all that is associated with the Day of Judgment, which Allah Almighty reveals in His Book or the Prophet (pbuh) informed about, such as death, resurrection, intercession, the Scale, the reckoning, Paradise, Hellfire, etc.
Sixth Pillar: Belief in Destiny; its pleasant and unpleasant aspects thereof
Allah Almighty says: {Indeed, We created everything with predestination.} [Ch. 54, Verse 49]
We believe that every worldly event or situation experienced by any creature occurs by the knowledge and predestination of Allah alone without any partner, and that those predestinations were written before the creation of mankind. We also believe that man has free will and he is the real doer of his actions, but all of that is not beyond the knowledge and will of Allah.
Belief in Preordainment is of four levels:
First: Belief in Allah's Knowledge that encompasses everything.
Second: Belief that Allah wrote all that will exist until the Day of Judgment.
Third: Belief in Allah's executive Will and His Omnipotence. Whatever He wills occurs, and whatever He does not will never occurs.
Fourth: Belief that Allah is the Creator of everything and that He has no partner in His creation.