If Christians mess up so much, how is Christianity supposed to change people?
Christians mess up constantly because Christianity isn't about perfect people. It's about perfect grace meeting broken humanity. The Bible never promised Christians would be flawless. It promised they'd be forgiven.
Romans 7 shows Paul, the greatest missionary ever, struggling with sin. The things I want to do, I don't do. The things I hate, I keep doing. That's verse 15. If Paul struggled, you think modern Christians won't? The difference isn't that Christians don't sin. It's what happens after. First John 1:9 says if we confess our sins, God is faithful and just to forgive us. Christians have a path back when they fall. Repentance isn't a one-time event. It's a lifestyle. Transformation isn't instant.
Second Corinthians 3:18 describes it as being transformed into His image with ever-increasing glory. Progressive sanctification. You're being changed from the inside out, but it takes time. A caterpillar doesn't become a butterfly overnight. It's a process. Here's the reality. Christians are under construction. Philippians 1:6 promises God who began a good work in you will carry it to completion. Not might complete it. Will complete it.
The church isn't a museum for perfect saints. It's a hospital for broken sinners. Jesus said in Mark 2:17 that healthy people don't need a doctor. Sick people do. He didn't come for the righteous but for sinners. Every Christian you see is in process. Some further along than others. Judge Christianity by Jesus, not by His imperfect followers. He's the standard. We're just people trying to become more like Him, failing forward, covered by grace.
God Bless