The short answer to this question is God defines sin. But how does He do it? Sin is defined in the word of God the Bible. The Bible was composed by many authors but these authors were inspired by the spirit of God, as though the spirit of God was writing through them. So the question is “Who wrote the Bible? Man or God?” The way I can explain this is that God wrote it using the agency of man. Before the New Covenant, there were prophets and holy people who spoke for God. Their words were recorded and when the books were compiled, including the books of the New Testament, we have the Bible. Because the Bible is God’s word, God Himself has preserved it throughout history. We understand who God is, and what is acceptable and not acceptable to God by reading the Bible. We learn this history of salvation, Israel’s deliverance and what God has done for the problem of sin, that every human being has a part in. Sin is clearly defined in the Bible, both in the Old Testament and in the New T