Harmonica seems flush with the idea that Christians are sinners. Believers are not under condemnation. We read in Romans that those in Christ are spared condemnation. They are not sinners. They may still offend God, i.e., sin, but they are not the sinners that the New Testament singles out as such. The sinners were the Jews who rejected the work and divinity of Christ. They were the ones - and still are the ones - outside the kingdom.
Sin is death, plain and simple. It is spiritual alienation. Paul said that sin (through the Law) killed him (Rm 7:11). Sin was spiritual death. It was death because the law was a law of sin and death. Obviously, Paul had not physically died when he wrote that.
For the Law of the Spirit of life has set you free in Christ Jesus from the Law of sin and death. (Rom 8:2)
Reconciled to God, as Paul declared to his Roman brethren, the saints are liberated from the Law, and therefore sin is not counted against them (5:11, 13). Before Christ, Jews practiced sin and therefore they practiced lawlessness (1 Jn 3:4).
Of course, the misconceptions of unbelievers are due largely to the misconceptions of Christians, who think that the New Testament is as much about them as it is about the apostles.