The disbelievers 2:6-7

[2:6] As for those who disbelieve, it is the same for them; whether you warn them, or not warn them, they cannot believe.
[2:7] GOD seals their minds and their hearing, and their eyes are veiled. They have incurred severe retribution.

What a pessimistic point of view : "...they cannot believe" as if they are blind that cannot see.
Even blinds could see if GOD wants,Even deaf could hear if GOD wants,there where miracles...
So why can't they believe? cause GOD sealed their mind...
Where is the free will?!
Why God seals their mind?
Why should they get severe retribution,if they don't have a free will?!

I think its the easy way...if you failed to convince a man,its probably cause he can't believe...
Instead of thinking your logic is not convincing blame the other person...