Commentators explain that when Jesus says, "I know whom I have chosen," he refers to those chosen for eternal salvation, not just for the office of apostle. While Judas was chosen as an apostle (John 6:70), he was not chosen for salvation. Scholars like Calvin note that this eternal election is the ultimate source of a believer's security and perseverance in faith, distinguishing them from those, like Judas, who fall away.