Fate and Divine Decree is Haqq (Truth), and it is Fardh (obligatory) to believe in it.
To bring Imaan in Divine Decree means that one should believe that Allah Ta'ala had predestined for mankind even before their creation, the good and the bad, Imaan and kufr, guidance and deviation, and obedience and disobedience; and all this has been recorded. Now whatever occurs in this universe, is doing so at the behest and wish of Allah Ta 'ala. Also - whatever happens, Allah Ta'ala knew about it in its entirety even before its occurrence.
The dictionary meaning of Taqdir is to measure or estimate. That occurrence that happens by desire and intention, is done with full understanding and measure. For example, a person wants to build a house. First a plan will be drawn so that the walls, etc. of the house can conform to some set standard. In the same way, when Allah Ta'ala intended to bring this universe into existence, He first set out a plan in His infinite Wisdom and Knowledge, and He measured each and everything from the time of inception until the end. Hence this 'design' and 'plan' of Allah Ta'ala is known as Taqdir.
Allah Ta'ala, in His infinite Wisdom and Knowledge had already meted out that at a certain time, a certain occurrence will happen at a certain place, or that a person after his birth will bring Imaan at a certain time, or that a person after his birth at a certain time will make kufr, etc.
As Allah Ta'ala says: "Indeed Allah had made everything in measure."
Taqdir is that Allah Ta'ala measured out everything of this universe even before its creation.
Qadha (Fate) is that Allah Ta'ala created and brought into existence everything according to His plan and measure. The dictionary meaning of Qadha is to create.
As Allah Ta'ala says: "And He created in them seven skies."
Hence the unanimous belief of the Ahlus Sunnah Wal Jama'ah is that - Fate and Decree are Haqq. There is not an atom, or even the smallest particle which is beyond the Taqdir of Allah Ta'ala. No one has the ability or potential to ward of or evade His Decree; or even to delay it or expedite it. Whoever He wishes, He grants guidance to and whoever He wishes He leads him astray. There will never be any questioning Him or asking for explanation.
However, He will question His bondmen regarding their actions. They will then be rewarded or punished for their good deeds or their evil actions. Nevertheless, Allah Ta'ala's Decree and Fate is Haqq. There can never be any chance of mistakes or miscalculations in Allah's actions. A human will first draw a plan prior to building a house, and Allah Ta'ala had planned this universe prior to His creating it, but between the planning and knowledge of man and that of Allah Ta'ala is a vast difference. The difference is that - man, due to some obstruction or the other, may have to change or alter his originally intended plans, hence the planning and knowledge of man can be incorrect and deficient. But when Allah Ta'ala intends to do something, there is nothing that will or can ever prevent Him, because the planning and Taqdeer of Allah Ta'ala can never be incorrect or deficient. His intentions always come into being and none can prevent it. Also, the knowledge of man is extremely deficient. There are many things that man only comes to know about after he had drawn up his plans, therefore, there will be a difference between the plan of man and the outcome. And the Knowledge of Allah Ta'ala, because it is All-Encompassing, therefore there will never be a difference between the plan and the outcome of Allah Ta'ala.
The Taqdir of Allah Ta'ala is Haqq. It is Fardh to bring Imaan in it. It is incorrect to present Taqdir as an excuse to our actions and deeds. For example, a man steals or commits Zina (adultery), and then he makes the excuse that this was written in his Taqdir. This excuse of his is unacceptable and insufficient to avert punishment from him. Indeed, Allah Ta'ala has decreed everything, but you did not have any knowledge thereof. When you had stolen or committed Zina, then you did so purely out of nafsaani (inner) desires and to satisfy yourself. At that moment you were unaware as to what was decreed for you. This is all an excuse, you have no knowledge of Taqdir. You committed this act voluntarily and by purpose. You were not forced into doing it, in fact you expanded your effort, strength, desire and gratification, hence for anyone to say that he/she was compelled by Taqdir to carry out a certain act is a lie and deception. The bondsman is not bound or compelled by Allah Ta'ala or Taqdir. Whatever the servant of Allah does, he does so of his own intention and accord, even though this intention and thought is made possible byAllah Ta'ala, nevertheless, the servant has the choice of carrying out the action, he is not forced.
Now remains the contention that since it is impossible for the servant to act contrary to Taqdir, is not this a form of being forced?
No this is not the case. Allah Ta'ala's Knowledge and planning is complete and flawless. There can never be a mistake in the Taqdir of Allah Ta'ala. Hence, to act contrary to this Taqdir is impossible. Taqdir is the information and 'data' of Allah Ta'ala. Knowledge follows that which is known. Information and data is something that follows what is related and transmitted, and it conforms to the reality. What is known does not follow the knowledge of it and what occurs and the reality of a situation does not follow the information and data of that incident. Just like how Allah Ta'ala has the knowledge of our actions and deeds, so too has He the Knowledge of His actions. Nevertheless, Allah Ta'ala does not force anyone on account of His knowledge. In this way, understand that the servant is not forced due to Allah Ta'ala's knowledge or Taqdir. Allah Ta'ala's Knowledge is on its place and the servant is on his place. In this world a person is not regarded as being forced. If people were being forced, then the governments would not need to make prisons for the transgressors. Allah Ta'ala has granted His bondsmen choice and ability, whereby he conducts his Deeni and worldly affairs. But, this choice of the servant is not with him by choice. Just like how a person has eyes and ears, not by choice but the actions he does with the eyes (looking) and ears (listening) are done by his choice. In a similar way, a person makes a choice to do something and he has the ability granted to him to carry it out, by his own choice. It is for this reason that it is said that a person has no choice in his qualities, but he has choice in his actions.
To believe that Allah Ta'ala is the Creator of man's actions, movements and animations does not necessarily mean that these movements are out of man's choice and power, because Allah Ta'ala has created both the power and the one who has the power. He has created both the choice and the one who has the choice. Power is one of the qualities of man, which Allah Ta'ala had created and Allah Ta'ala has created both man and his qualities. All this is in His Control. If man carries out an action through this Allah-given quality of power of his, then according to all learned men, this is by his (man's) choice, and not an involuntary action. In short, we say that the existence of man, his actions and qualities, although we relate all this to Allah Ta 'ala, does not mean that man is helpless.
Allah Ta'ala's Power and Will is connected to the existence of man, but owing to this connection man does not become obliterated. In a similar way, by Allah Ta'ala's Power and Will being connected to man's power and choice does not make man helpless. Man is however the servant and the creation of Allah Ta'ala. It is not possible for the creation's existence and qualities to supercede the Encompassing Power and Will of the Creator. Those who aver that man is the creator of his own actions and that man's actions have no relation to the Power and Will of Allah Ta'ala (na'udzubillah) , are trying to say that the creation can supercede the Creator's Power and Will.
The entire Ummat unanimously agree that:
"Whatever Allah Ta'ala Wills comes to pass and whatever He does not Will does not occur."
The Mu'tazilahs (a deviant group of corrupt beliefs) believe that the actions of the servant are excluded from the Will of Allah Ta'ala. May Allah Ta'ala save us all.
Allaah Ta'ala has created this universe with different things in it, the size and shape of everything is different for one another. The ability of each thing also differs from the next. Take the example of a tree which has thousand different types of wood, some are used for burning, others for making wooden boards, others for roofing, etc. Everyone agrees that if everything in this universe had the same qualities and conditions, then this universe would not be able to function properly and smoothly. Now remains the contention that why are the abilities of everything different. This answer has still not been fathomed until today.
Muslims say that all this is in the Wisdom of the All-Knowing and All-Wise. The atheists say that all these different abilities are due to the movements of the blind and deaf matter. Just as Allah Ta'ala, in His Infinite Wisdom has created the abilities and shapes of trees and stones different from one another, He has also created the abilities of man different from one another. Some He made intelligent and sagacious, whilst others He made stupid and ignorant. Some He made susceptible to the Haqq and others to kufr. He made - the heart of some clean and clear, whilst that of others are black and dark.
"None can ask about what He does, whilst they are at answerable."
An Objection And Its Answer
The objection is that the actions and speech of man is dependant upon their respective abilities. And all this is pre-destined, and not in the power of man, hence why is there an indictment against the Kuffar, when they are in actual fact helpless and without choice.
ANSWER - Allah Ta'ala has created two types of creations. Some are those which Allah Ta'ala did not give any knowledge or (intelligent) qualities, like trees and stones. This type of creation will have no questioning or retribution. They will not be rewarded or punished. The other type of creation is that one on whom Allah Ta'ala placed intelligence and choice, like man and jinn. For this creation Allah Ta'ala granted them intelligence, choice and power. They have also been given limbs and organs, whereby they willingly carry out actions, and these actions are attributed to them. For example, they say that we have done this action with our hands, or that "I have said this", or "I did that", etc. They accept and agree that whatever (worldly) reward or recompense is due upon them for any action carried out, it is for them and that they deserve it. But suddenly when it comes to reward or punishment in the Hereafter they say that we are helpless. Do they not realise that Allah Ta'ala has granted them intelligence and choice in this world so that they may follow and carry out the Commands of Allah Ta'ala , and then be liable for either reward or punishment? Just like how in this world one is not merely rewarded because of his ability and potential, so too is a person not punished in the Hereafter simply due to his ability. Reward and punishment will be meted out only after one carries out good or bad actions. A person is not rewarded merely because he is brave and strong. He has to go out into the ring and prove himself. In a similar way, a person will not be rewarded by Allah Ta'ala merely on account of his ability. He must carry out actions that will warrant a suitable retribution.