Can a Christian sin?

Over the years, I always thought: Why do I not act like Christ-like manner at times? I have learned and realized that Christ in me does not mean that I am no longer without sin. My old sinful nature is not ripped out from my heart. Christ is in my heart and with the help from the Holy Spirit, Christ changing me from the inside and lives through me. So the answer is YES....if a Christian is not careful and forget. This is where Paul is talking about in Romans 7. Old Creature (Following flesh's desires) = Self-Centered New Creature (Following God's desires) = God-Centered From our old creature, we learned worldly desires and causing us to think more worldly (still do). We are still sinners but forgiven sinners when we accept Christ as our Lord and Savior. A disciple must understand that God is both holy and loving; that I am a sinner, are made in the image of God; that Christ's death was the substitute payment for my sin; and that because of Jesus' payment, I am granted access to the heart of God. Sin by accident as part of our sinful nature: Those who are in Christ Romans 7:18 I know that nothing good lives in me, that is, in my sinful nature. For I have the desire to do what is good, but I cannot carry it out. Galatians 5:17 For the sinful nature desires what is contrary to the Spirit, and the Spirit what is contrary to the sinful nature. They are in conflict with each other, so that you do not do what you want. We just need to be looking at our adequacy in the Holy Spirit, which will always be in us. This is God's design, and it pleases Him to do so that we can rely on the Holy Spirit. "Watch and pray that ye enter not into temptation: the spirit indeed is willing, but the flesh is weak."--Matt. 26:41. Biblically, Christians are no longer "in the flesh": "You are not in the flesh but in the Spirit, if indeed the Spirit of God dwells in you. But if anyone does not have the Spirit of Christ, he does not belong to Him" (Rom 8:9). The Greek word for "dwells" is okv (oike), which means "I inhabit." "If Christ is in us, though the body is dead because of sin, yet the spirit is alive because of righteousness" (Romans 8:10). In other words, our human body is subject to death (and is already dying) because of sin, however our spirit is alive in Christ. We have eternal life in our possession, even though our body is dying because of sin. However, as Christians, our spirits are fully alive and thriving "because of righteousness"--because HE is justified and therefore already has "passed out of death into life" (John 5:24). "My temorary body is decaying at the same time, my inner being is being renewed day by day" (2 Cor 4:16). "If we live in the Spirit, let us also walk in the Spirit." Galatians 5:25.