God has "saved us and called us with a holy calling, not according to our works" (2Ti 1:9). Israel didn't apprehend it because "they did not pursue it by faith, as though it were by works" (Ro 9:31). "Seeking to establish their own [righteousness], they did not subject themselves to the righteousness of God" (10:3). "He chose us in Him before the foundation of the world, that we would be holy and blameless before Him" (Eph 1:4). He called us "according to His own purpose and grace which was granted us in Christ Jesus from all eternity" (2Ti 1:9). Jesus "was foreknown before the foundation of the world" (1Pe 1:19). But don't "neglect so great a salvation" (Heb 2:3). At a banquet there was a person "not dressed in wedding clothes" (Mt 22:12). The king said, "'bind him . . . and throw him into outer darkness'" (:13). "'Many are called but few are chosen'" (:14).
What guaranty is there that you can follow through with your commitment? Paul's confidence is "that He who began a good work in you will perfect it until the day of Christ Jesus" (Php 1:6). It depends on God. "It is no longer I who live, but Christ lives in me" (Gal 2:20). It works because God has "sealed us and gave us the Spirit in our hearts" (2Co 1:22) "as a pledge of our inheritance, with a view to the redemption of God's own possession" (Eph 1:14). Because Jesus "continues forever . . . He is able to save forever those who draw near to God through Him" (Heb 7:24-25). "Who will separate us from the love of Christ?" (Ro 8:35). Nothing "will be able to separate us from the love of God" (:38). "'This is the will of Him who sent Me, that of all that He has given Me I lose nothing, but raise it up on the last day" (Jn 6:39).
Where does the threat to a believer come from? It is because "they themselves are in the world" (17:11). Therefore Jesus asked the Father to "'keep them in Your name'" (:11). As a result, "'My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father's hand'" (10:29). Paul was "convinced that He is able to guard what I have entrusted to Him until that day" (2Ti 1:12). Peter said we "are protected by the power of God through faith" (1Pe 1:5). Also, "your adversary, the devil, prowls around like a roaring lion, seeking someone to devour" (5:8). "But He who is born of God keeps him, and the evil one does not touch him" (1Jn 5:18). "Greater is He who is in you than he who is in the world" (4:4).