Can you lose your faith in Christ? No, not if by lose you literally mean lose. We cannot simply forget our faith. We also cannot have our faith stolen from us by any outside force (John 10:28). Believers need not fear that they will lose their salvation even if they commit a sin. Christ died on the cross to save us from all our sins; past, present, and future. However, if we profess to be a follower of Christ and live the life of a sinner, we are lying to ourselves and others (1 John 2:3-5).
The scriptures assure us that we can't simply lose our salvation or have it stolen from us. But can we give up our faith? Let's examine some of Hebrews. In almost every chapter in Hebrews, the writer warns his readers not to leave their faith. Passages such as Hebrews 2:1-3; 3:6-15; 4:1, 11-14; 10:26-31; 12:25. But this isn't just confined to Hebrews. 1 Corinthians 15:2, Galatians 5:4, Colossians 1:23, and 1 Timothy 1:19 are just to name a few others.
I think the strongest passage saying one can give up their salvation is in Hebrews 6:
4 For it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit, 5 and have tasted the good word of God and the powers of the age to come, 6 if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame.Starting in verse 4, we encounter a frightening warning. If someone who has been enlightened, who has tasted the heavenly gift, who has partaken in the Holy Spirit, falls away, it is impossible for them to be renewed to repentance. Now this forces us to ask, who has the Holy Spirit? Only believers partake in the Holy Spirit (Ephesians 1:13). I believe this passage is clearly speaking of believers, for it is only believers who partake in the Holy Spirit. I think the passage makes it clear that a conscious decision to leave Jesus Christ is possible.
7 For the earth which drinks in the rain that often comes upon it, and bears herbs useful for those by whom it is cultivated, receives blessing from God; 8 but if it bears thorns and briers, it is rejected and near to being cursed, whose end is to be burned.
9 But, beloved, we are confident of better things concerning you, yes, things that accompany salvation, though we speak in this manner. 10 For God is not unjust to forget your work and labor of love which you have shown toward His name, in that you have ministered to the saints, and do minister. 11 And we desire that each one of you show the same diligence to the full assurance of hope until the end, 12 that you do not become sluggish, but imitate those who through faith and patience inherit the promises.
The saddest part of this passage, is it looks like those who have experienced the gift of salvation who decide to turn away from Christ can never again repent and put their faith in Jesus. People like Bart Ehrman, because of their own hard hearts, have abandoned their hope. Lucky for the believer, the writer does give us good news in this passage. God does not forget His followers' works that are done in His name. Let us not be sluggish, but through faith and patience let us inherit the promises of the Lord.
And remember, as children of God, we should have the highest confdence that we are saved in Jesus Christ, as Paul states so eloquently in Romans 8:35-39. No outside force can remove us from Jesus Christ. But the Holy Spirit has warned us that we can seperate ourselves from Chrst Jesus.