What is perseverance of the saints?A Scripture-grounded answer about perseverance of the saints

Perseverance of the saints is the doctrine that those who are truly saved will persevere in faith until the end and never ultimately fall away. It is the 'P' in the Calvinist TULIP. This does not mean believers never struggle, doubt, or sin — it means God preserves them through those struggles so that they ultimately arrive at glory. Philippians 1:6 grounds this: 'He who began a good work in you will bring it to completion at the day of Jesus Christ.' Those who appear to fall away were never truly saved to begin with (1 John 2:19).