Everyone being aware of it doesn't mean it would happen all the time. I'm very aware of it and if selected I would still hear the case as dispassionately and impartially as possible, as I view a jury trial as a civic duty and an important cornerstone of criminal justice.
But I suspect the question you're really asking is "What if every juror refused to convict in any crime?" And the answer to that question is that jury trials would no longer be a thing if juries weren't useful. Judges would hear the cases and rule themselves (and judges already rule summarily in many trials today).
Have you ever been selected for jury duty? I haven't, so I can't speak to the screening process.
In cases of capital punishment I wouldn't be surprised if they screen out people who are against it, since it would be a conflict of interest. A jury's only purpose is to determine whether someone is guilty of a crime, not to weigh in on sentencing. Although I'm pretty sure sentencing comes later anyway.