The concept of a backsliding Christian has long existed within the church, yet does not appear in the New Testament. Instead, 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.
What does the Bible say about backsliding Christians? Are they still saved?
However, in the New Testament the emphasis is on believing in Jesus as Lord and then living for Him (John 3:16; Ephesians 2:8-9). Believers are no longer condemned (Romans 8:1) and nothing can separate a believer from the love of Christ (Romans 8:38-39).
The New Testament directly answers the issue of a genuine believer who sins. First John 1:8-9 teaches, "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." First, we admit that even as believers we often sin. Second, we confess our sins and experience forgiveness and cleansing.
In some cases, however, a person who has claimed to be a Christian for some time later abandons the faith and claims to deny Jesus Christ. In this case, 1 John 2:19 offers the proper response: "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." In other words, a person who claims to be a Christian and later leaves the faith shows he or she was never a genuine believer.
In fact, the apostle Paul taught the church at Corinth to examine themselves to make certain they had believed: "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.
This is the New Testament emphasis in dealing with sinning Christians. The responses are to examine oneself to make certain they are a believer and as a believer to repent and turn from sin. 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).
Is there such a thing as a carnal Christian?
Do the Bible's warnings against apostasy imply that salvation is not eternally secure?
Is it possible to 'give back' salvation?
Does the Bible teach eternal security?
Is salvation by faith or works or both?
Truth about Salvation