For we intuitively know that the law is rational, but I, on my part, am fleshly, having been sold under the sin [nature] (Romans 7:14).
The law pertains to the spirit—the rational, logical center of a human being (1 Corinthians 2:11). Its standards are righteous. However, because we pertain to the flesh, we have been sold under the sin nature. Therefore, the law does not produce good in us; instead, the sin nature uses the law to deceive us.
Through our own fleshly desires, the sin residing within us seeks to produce a form of self-righteousness, which develops a system of traditions that justify violating the law in pursuit of an appearance of righteousness (Matthew 15:3).