How can one be a Christian and believe in Christ but still have problems with sin, sinful habits, and doubt? I know Scripture says that we become new creatures in Christ, but what if one does not feel like a new creature in Christ because of sin and spiritual doubts? Does this mean one is not meant to be saved or was never truly a Christian?
As you rightly say, the Bible affirms that believers are indeed “new creatures” in Christ. 2 Corinthians 5:17 and Ephesians 2:10 use this kind of language. The Bible also affirms, as does our experience in living as believers, that we remain sinners with a sinful nature, weakness of faith, and spiritual challenges when we’re tempted to sin or doubt God’s promises. Passages like Romans 7:15-25 and Hebrews 12:1-12 testify to this ongoing reality.
You ask “how” this can be, and you seem to be making a logical deduction that if someone is “truly” saved or “truly a Christian,” then a kind of sinless perfection should immediately result in our thought patterns and lifestyles. That may be logical, but it is not biblical or true. It is a false conclusion to be cast aside. The Christian life is one of warfare against sin and Satan and against our own sinful nature that opposes God’s will and is indeed a terrific cross to bear this side of glory. This struggle is also used by God for disciplinary purposes to further our progress in Christian character and endurance when coupled with an active use of the gospel of Jesus Christ.
Historically, some have emphasized the passages about our being “new creations” to the exclusion of those passages that speak of our continuing sinfulness (despite our being justified or forgiven in Christ) and have taught a kind of so-called “perfectionism” or “complete sanctification” set of ideas. We believe that is false. Instead, we teach that ALL Bible truths are to be received and embraced rather than adopting some while denying or distorting others. We heartily invite you to accept the same understanding.
Above all else, focusing on your final words, we urge you to stop thinking you are not a true believer simply because you still contend with weaknesses and sins on a daily basis. Continue to focus on Christ’s perfect work on your behalf, rejoice in the unconditional declaration that you are 100% forgiven for his sake, and do not see your sins as clear evidences of unbelief. A focus on Christ and the unconditional good news of his saving work will also strengthen you in your daily battles against sin. We do not expect perfection this side of heaven, but we do expect and may enjoy progress and growth in godliness.