What does the Bible say about backsliding Christians?

from the old testament

• The closest biblical reference to a "backslider" is found in the Old Testament account of Jeremiah 8:9: "The wise men shall be put to shame; they shall be dismayed and taken; behold, they have rejected the word of the LORD, so what wisdom is in them?" In this account, the Israelites had turned their backs on God. The Lord promised judgment upon them as a result. They would later be removed from the land and deported to Babylon as slaves.
• Only God knows people’s hearts (1 Samuel 16:7).
• God calls the Israelites to return to Him in several key passages (Hosea 14:1–2; Jeremiah 3:12; Isaiah 44:22). These passages reflect God’s call for repentance and His readiness to forgive and restore the Israelites if they turn back to Him.

from the new testament

• The New Testament emphasizes believing in Jesus as Lord and then living for Him (John 3:16; Ephesians 2:8–10).
• Believers are not condemned (Romans 8:1) and nothing can separate a believer from the love of Christ (Romans 8:38–39).
• Regarding believers and sinning, 1 John 1:8–9 says, "If we say we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins and to cleanse us from all unrighteousness." Even as believers we often sin. When we confess our sins, we experience forgiveness and cleansing.
• First John 2:19 addresses people who walk away from the faith or the fellowship of believers: "They went out from us, but they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might become plain that they all are not of us." Only God knows the heart. From the outside, we cannot tell whether someone who seems to be backsliding is a believer in a state of rebellion or struggling with doubt or if they were never a believer to begin with. Whatever the case, we can pray for that person to repent and turn to the Lord. We can be the agents of reconciliation that God calls us to be (2 Corinthians 5:18–19). If they are saved and wandering, they need to be cleansed and their fellowship with the Lord renewed. If they were never saved to begin with, they need to be reconciled with God.
• The apostle Paul taught the church at Corinth to examine themselves to make certain their salvation: "Examine yourselves, to see whether you are in the faith. Test yourselves. Or do you not realize this about yourselves, that Jesus Christ is in you?—unless indeed you fail to meet the test!" (2 Corinthians 13:5). He did not assume every person in the church was a true believer. Instead, Paul taught the Corinthians to make certain they had truly believed. His focus was not on whether a person had lost his or her salvation, but whether a person had truly believed at all.
• We should be cautious to not let our own hearts deceive us to think that we are in Christ when we do not intend to follow Him (Matthew 7:21–23)
• Salvation is by God's grace through faith (Ephesians 2:1–10), but that faith is not mere profession; it is belief that results in change (2 Corinthians 5:17; James 2:14–26). Believers are to put off the old self and replace this life with the new self: "Do not lie to one another, seeing that you have put off the old self with its practices and have put on the new self, which is being renewed in knowledge after the image of its creator" (Colossians 3:9–10).
• We are called to "work out your own salvation with fear and trembling, for it is God who works in you, both to will and to work for his good pleasure" (Philippians 2:12–13).
• We are also called to not continue in sin for those who continually, unrepentantly, without conviction engage in sin show they are not saved (1 John 3:6–9).
• Those who are saved have the indwelling Holy Spirit, who works in them to help them know, love, and obey God (Romans 8:28–30; Ephesians 1:3–14; Philippians 1:6). The indwelling Spirit cannot be removed and is an assurance of our salvation (Ephesians 1:13–14).
• We can trust that those who are in Christ are completely secure (John 10:27–30).

implications for today

Watching a Christian backslide can be deeply unsettling, as it often involves witnessing a loved one struggle with their faith or stray from their spiritual commitments. It can cause us to question our salvation or God’s goodness as we wrestle with knowing if the person was saved to begin with or the unknown of not knowing if they will return. This situation serves as a powerful reminder for us to examine our own faith, resting assured that nothing can take our salvation away. Yet, we also must remember that after salvation, there is a process of maturation called sanctification. Sin is still a reality in the life of believers and so is doubt. So, while salvation is secure, the process of sanctification and spiritual growth is lifelong and marked by ups and downs. Salvation does not bring a state of immediate perfection. Instead of panicking over setbacks, we should focus on the continuous work of the Holy Spirit in our lives, embracing both the progress and the struggles as part of our spiritual maturation. This perspective helps us maintain hope and compassion, both for ourselves and for those experiencing difficulties in their walk with God.