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.