Mohsen
السلام عليكم ورحمة الله وبركاته
You have to understand how free will works within God's will to understand why.
I had a wall of text to explain it, but its just too advanced for someone who is not a believer to begin with. Devout christians and biblical scholars have a hard time digesting it even.
Ah, I can simplify that:
Johnathan goes to a takeaway, he sees three options:
1) burger meal
2) steak meal
3) chicken salad meal
the choice is his, because God gave him free will. What he must do is make the best choice for himself.
God has the over-riding will which will determine the fate of johnathans choice.
if Johnathan chooses:
1) burger meal - he will end up with a sore belly but be fine the next day
2) steak meal - he will end up with food poisoning and have to take a day off work the next day
3) the chicken salad meal - he will be fine.
Johnathan has no way of knowing the result of his choice! He just wants to eat!
It is God who decides the result of such choices, it is we who choose! Free will, is basically, a game of "Multiple Choice" - so choose wisely!
God blessed us Muslims to understand these things, things which devout Christians and biblical scholars have no clue how to understand.
God bless