If Allah S.W.T created us so he created our brains which will determine our acts and our decisions, then why we will be punished for our mistakes?

Allah (swt) created man with a mind to determine between right and wrong... Man has control over his actions, hence, he is not compelled to jump or sit. Therefore, he decides to do good or bad.

Man's actions revolve around two spheres: one dominates him and the other he dominates. The one that dominates him is the one that entails al-Qadhaa because man has no control over it. As for the other sphere, man chooses what to do and what not to do.

Allah knows best.

read more here https://www.islamiqate.com/812/what-is-different-about-taqiuddin-nabhanis-book-nizam-islam

The question is kinda confusing, so in my understanding your question is "if Allah predestined our fate then we don't have any free will and why is our fault if we sin?"

So we know that Allah has written everything that will happen till the day of judgement in Preserved Tablet (al-lawh al-mahfooz). Then the question here is, why is my fault if I sin? because Allah already predestined it.

Let's explain this with an example:

"You went to shopping"

Now you went to shopping is because Allah already written it? The answer is yes. But now is the IMPORTANT PART. Allah already knew you would go to shopping at that specific time, because Allah has the knowledge of unseen. He knows already that you will do that. So he has written it. It's not that Allah has written that's why you are doing it, It because you will go shopping, that's why Allah is written it. Allah already know what will happen, that's why he written it. Allah knows that what will happen, when will happen and in what manner it will happen. He knows every atom size details of everything.

(Also if I didn't understand your question, tell me)

Thats a very good question and is valid indeed .It makes one think that we are in a game that god has created from the very scratch and everything about its result is known before it even starts.The argument is then why would he punish people for their actions ,since he created for them the conflict inside them and not as angels who are always good.

I think you can think of it that Allah is fair ,you can see his wisdom in life.The Lion eats the gazelle ,however its good for both the lion and the gazelle .Life has wisdom in it,so Allah is really just going to put you in your right place, he has a plan for you,so weather you are going to heaven or hell ,it will be the best thing for you ,maybe some purification is required in hell ,you don't know ,but it will be the right decision for your specific case ,and there are stages in hell as there are in heaven,so its not a narrow 2 way road.

Subconscious mind gives us many options and then we choice from its we don't create decision but choice from available options .this is our Destiny sir ;Do am i wrong ? "you will not wills unless its Allah's will "

I'd say if we didn't have freewill then heaven and hell would be for no reason. If we didn't have heaven/hell then this world would be an unjust world.

Ultimately this question is a question of conscience. Look into yourself, do you truly think you are not free. I doubt that. I know if one thinks too much of it, it becomes complicated. But believe that won't get you anywhere.

This argument presumes that our mind is the brain, but this is an assumption that has been contested since much earlier in history by the arguments of Neoplatonic and, later, Muslim philosophers. According to this perspective, our free-will is based on our ability to tell right from wrong by the virtue of our thinking mind which is of a different nature than the material brain (and any other material entity) despite closely interacting with the brain for its functioning in the natural world.

This argument, like many others of this kind, comes from the Christian world. It is also quite old.

It may have appeared among the cathars. In the 12th century in south western France, the cathars said that everyone would go to heaven. It is not clear whether they had this argument or not, though, since the pope launched a crusade against them and they all died (I am happy to live in this century).

When the reform appeared, some protestants (calvinists I think ) used this argument to say that god knew before our birth whether we would go to heaven or not.

Then, atheists came along...

Christians usually answer this by saying that god lets us have free will. This is where the true underlying question appear. Are our thoughs determined only by our experience, or are they also appearing out of nowhere (in which case we have free will) ? In the first case, the atheist is right. Which leaves us with the second case.

If some thoughs appear out of nowhere, god knows when they will appear, what they will be, and what effect they will have on you. They are just like an experience, they come up and influence your other thoughts. So god judging you means he is judging thoughts he knew about before you were born and other stuff he knew about before you were born. So the atheist is right.

Unless you are willing to admit that god is not omnipotent and omniscient. In that case, the atheist is right again.

As you can see, there is no way to win a rational argument against an atheist. It is their realm. I am sure he has many other rational arguments just as undeniable for you.