Instead of being perfected,
other translations speak goal. The idea is that human effort or works of the flesh are needed in order to make progress in the Christian life.1 In the context of the Galatians, they thought that circumcision and obedience to the old covenant law would bring them closer to God, as if the Spirit is not sufficient. Paul responds with a question that is meant to help them understand that the Christian life is supernatural (Spirit-led) from start to finish.2
3 Etes-vous tellement dépourvus de sens? Après avoir commencé par l'Esprit, voulez-vous maintenant finir par la chair?