Is there such a thing as an ex-Christian?

from the old testament

• The Old Testament doesn’t directly address “ex-Christians,” since that concept is tied to faith in Jesus Christ revealed in the New Testament. However, it provides foundational insights about God’s covenant, faithfulness, and the permanence of His promises. For example, many Israelites failed to follow God despite being part of His chosen line (Deuteronomy 9:4–6; Judges 2:10–12). A mere outward association with God’s people isn’t enough; the heart must truly follow Him.

from the new testament

• Only God can accurately judge the salvation of a professing believer, but a true Christian cannot become an ex-Christian because Jesus said of true believers: "I give them eternal life, and they will never perish, and no one will snatch them out of my hand. 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. I and the Father are one" (John 10:28–30).
• Many will go to the grave never receiving salvation—ultimately rejecting Christ (1 Corinthians 1:18–25), and some who fall into this category are those who grow up in the church and later “walk away from the faith.” However, if they never received Jesus Christ as their personal Savior in the first place, they are an unbeliever—not an “ex-Christian.”
• Christians are ultimately new creations in Christ, and nothing can strip away that identity (2 Corinthians 5:17). Sanctification is continual, and we will likely have hard and trying seasons in our faith walk, but even if we tried to walk away from God we can’t because His Holy Spirit is living within us and He has permanently changed our identity. We can’t go from an old creation to a new creation and then reverse the process. Once God’s work is done in our life it is permanent, absolute, and eternal.
• James makes the point that even demons believe in Jesus—yet faith without works is dead: “But someone will say, ‘You have faith and I have works.’ Show me your faith apart from your works, and I will show you my faith by my works. You believe that God is one; you do well. Even the demons believe — and shudder! Do you want to be shown, you foolish person, that faith apart from works is useless?” (James 2:18–20). Ultimately, someone can say they believe in Jesus and even follow His commands—but if there has been no inner heart transformation by the Holy Spirit, salvation has not taken place.
• First John 2:19 says: "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." One can go through the motions of a Christian lifestyle, but if he or she denies Jesus, the Son, they do not have God the Father and are therefore not a child of God (1 John 2:23–25).

implications for today

Some people have an association or connection to a Christian church but later renounce it and turn their heart against Christ and His church. Other people have "sampled" and "experienced" Jesus Christ without actually receiving Him as their Savior or making Him the Lord of their life. Then there are others who do good works and think that will guarantee them salvation, but Jesus warned that this is not the case (Matthew 7:15–23). If people in any of these cases are choosing to forsake a previous, Christian-looking lifestyle, but have not ultimately believed in Jesus Christ as their personal Savior, they are not a true “ex-Christian.”

While all Christians may experience seasons of difficulty, feeling far away from God, or falling into sin, true Christians return to Him in a state of repentance. Their hearts are inclined to know Him more and walk through the struggles of life with Him as their guide and source of peace. True Christians represent, serve, and follow Christ. Once a person has completely believed in and trusted Jesus as their Savior, experiencing the fullness of His grace and love, they can never renounce their faith—their identity and eternal fate are secure in Christ (2 Corinthians 5:17; John 10:28–30).