For the gifts and the calling of God are irrevocable Romans 11:29
He who calls you is faithful, who also will do it. 1 Thessalonians 5:24
Let us hold fast the confession of our hope without wavering, for He who promised is faithful. Hebrews 10:23
Being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ; Philippians 1:6