Probably because Scripture says so and she happens to believe all of it.
God isn't just a merciful God, as you truncate his attributes incessantly to fit this to your narrative. He exercises mercy on whom he wills, and hardens some not showing them mercy. That's a fact, and he is just to do so. He has full right to judge any man in sin, and exercise justice on any man at will without them having an opportunity to "choose" or even hear the Gospel.
Note everyone the text in Exodus 33:12-23; Romans 9:11ff.
God has elected whom he willed to save by his purpose, counsel and will, based upon nothing good in them, not based in that they would choose him, but solely based in his purpose, counsel and will, and is pure unmerited favor, aka grace.
You don't like those facts and try to put him in a box to fit into your logic of what you deem to be "fair."
Guess what?
God doesn't bow to any mans demands of what he may deem to be fair, or of what man may deem unfair and then claim he cannot be God. He's God in spite of mans demands.
He does as he wills as said above. One can believe the testimony of Scripture that proves this, or one can be the man in Romans 9:19-20.
@Rosemaryx I am glad to see how you have grown in Scripture, grace, knowledge and haven't allowed truncated versions of "God" and man made narratives of how he should act to affect you. Stick to the whole counsel of God. Do not feel intimidated by
any man.