That seems to be the same question Paul was expecting of his readers in Romans. He probably asked the question because in his preaching he came across the same question as yours 1,000 times. Notice he never answers the question.”How can God judge as guilty, those whom he has not predestined to faith in His Son?"
This is the ESV (English Standard Version)
Rom 9:18 So then he has mercy on whomever he wills, and he hardens whomever he wills.
Rom 9:19 You will say to me then, “Why does he still find fault? For who can resist his will?”
Rom 9:20 But who are you, O man, to answer back to God? Will what is molded say to its molder, “Why have you made me like this?”
Rom 9:21 Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use?
Again, "why does He still find fault" sounds exactly like your "How can God judge those He has not elected."
What was Paul's answer? He basically rebukes the person for asking the question in the first place: "But who are you, O man, to answer back to God?"
Does not the potter (creator of the universe) have the right to make one for honorable use and another for dishonorable?
You people who get upset at this idea would answer Paul with an emphatic NO. God does not have the right.