The Greek verb aphorizo combines apo (from) and horizoo (to bound, mark out), meaning to separate, divide, set apart, or appoint by marking a boundary. It appears ten times in the New Testament in a range of contexts: God setting Paul apart from birth (Galatians 1:15), the final separation of the righteous from the wicked (Matthew 13:49), and synagogue exclusion of believers (Luke 6:22).
The double edge of aphorizo is striking: it describes both divine election (Galatians 1:15 — "set me apart from my mother's womb") and final judgment (Matthew 13:49 — the angels "will separate the wicked from the righteous"). The same action — boundary-drawing, separation — is both gracious calling and solemn reckoning. Paul's testimony in Galatians 1 is that every believer has been aphorizo'd by God before birth for a specific mission in the body of Christ.