I think it’s important (and helpful for evangelism) to think about a correct understanding of sin. While we can refer to breaking the commandments of God as sin (murder, idolatry, etc.), it is probably more correct to consider these active manifestations of our rebellion against God as “sins”. Where “Sin” is the condition or state in which the human race is in since the fall of Adam and Eve, “sins” are the various manifestations of this condition that naturally flow from our fallen condition. Paul talks about the two states or conditions in which people are before God in Romans 5:12-21: We are either “in Adam” and thus condemned by the Law and under God’s judgement and wrath; or we are “in Christ” and free from the condemnation that the Law brings and we receive Christ’s righteousness as a free gift accepted by faith. The Law of God, as this website correctly asserts, was introduced by God to expose the state of Sin. The Law does this by showing us our various and many “sins”. We need to have the right distinction in our minds when explaining the gospel. There is Sin (our sinful condition) and there is sin (the various manifestations of our sinful condition).
It may also be helpful when doing evangelism to reflect upon Romans 6 where Paul talks about us being either slaves to sin or slaves to righteousness. Most Australians wouldn’t take too kindly to the idea of being a slave. We could safely assume that many Australians consider themselves free to be whoever they want to be. Therefore, it could be effective to outline the reality of human slavery to sin and demonstrate that any perceived “freedom to do whatever I want” is actually only an illusion of freedom. Ask your non-Christian what they think freedom is and then use Romans 6 to show them that there’s no such thing as freedom! A human being is either a slave to sin which leads to death and hell, or a slave to obedience to the gospel of Christ which leads to everlasting life – there is no middle ground! Another useful section of Scripture is John 8:34: “I tell you the truth, everyone who sins is a slave to sin”. Only once a person sees their true condition can they then understand the true freedom that the gospel brings: “So if the Son sets you free, you will be free indeed” (John 8:36).