How do we know that the doctrine of Preservation of the Saints is true?
Answered in 1 source
The doctrine of Preservation of the Saints assures that God will keep the elect in faith until the end, as found in Scripture's promises.
The doctrine of the Preservation of the Saints, one of the points of TULIP, teaches that those truly saved will persevere in faith until they reach eternity with God. This is grounded in the assurance given by Scripture that the Holy Spirit writes faith on the hearts of the elect (Ephesians 2:8). Because of this divine action, the argument stands that if God has unconditionally removed the guilt of sin, He will likewise preserve faith in His elect. Romans 8:28-39 emphasizes this assurance that nothing can separate the elect from the love of God, confirming the certainty of their salvation.
Commentary