Why did Paul call himself “the chief of sinners”?

Some point to 1 Timothy 1:15 to make the argument that Christians are called “sinners” in the New Testament. However, Paul only referred to himself as a sinner in the 1 Timothy passage because of his history of persecuting the church (Galatians 1:13). He was referring to his condition before salvation. We believers are not sinners by nature anymore. We are saints who sometime sin.