This final point states that the elect that God chose cannot permanently fall away from Him. This goes along with the idea of irresistible grace. This idea is greatly debated even outside of the Calvinist beliefs. There are many verses to support this idea, but one of the most commonly used is John 10:28, which states: “I give them eternal life, and they shall never perish; no one will snatch them out of my hand.” This verse implies that no one can take the saved out of Jesus’ care, not even the devil. There’s also Philippians 1:6, “Being confident of this, that he who began a good work in you will carry it on to completion until the day of Christ Jesus”. This tells us that God finishes what He starts. If God starts a transformation in you, He will finish it.
Now, there’s one verse that seems to completely go against the idea of the perseverance of the Saints, and that’s Hebrews 6:4-8: “It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, who have tasted the goodness of the word of God and the powers of the coming age and who have fallen away, to be brought back to repentance. To their loss they are crucifying the Son of God all over again and subjecting him to public disgrace” This verse seems to clearly say that people who have shared the Holy Spirit can fall away from the faith. But I’d like to offer a new perspective.
There are many ways someone can look at Hebrews 6, but there is one way that I believe works in harmony with the rest of the Bible. That is, to look at it as a sort of means to get the outcome or promise God describes. There’s a story in Acts 27. Paul is on a boat, the crew got scared the ship would be destroyed by rocks, but Paul was told by an angel that no one would die. Despite knowing no one would die, when men tried to jump off the boat Paul said “Unless these men stay with the ship, you cannot be saved.” Even though God promised everyone would be safe, the means by which He kept people safe is through warning. The same could be applied to Hebrews 6 when talking about perseverance of the Saints. God promises we will remain saved, but the means by which that happens is through warning.
Another thing people bring up are stories of people who were Christian and fell away, which doesn’t seem uncommon. What I’d like to offer on that point is that if they were able to fall away, maybe they never truly accepted Christ to begin with. We can never know someone’s true heart, only God can do that, but their actions and the fruit of their life can speak to their heart posture.