Actually, it is about "the myth of 'Original Sin,'" which asserts that a person emerges from the womb spiritually dead.
"They (Adam & Eve) being the root of mankind, the guilt of this sin was imputed, and the same death in sin and corrupted nature conveyed to all their posterity, descending from them by original generation" [emphasis added] (The Westminster Confession of Faith; VI/3).
However, Paul tells a different story:
"For I was alive without the law once: but when the commandment came, sin revived, and I died. And the commandment, which was ordained to life, I found to be unto death. For sin, taking occasion by the commandment, deceived me, and by it slew me" (Ro.7:9-11).
Paul is not speaking of "physical" death because he was alive physically when he wrote those words. He is speaking about breaking one of the Ten Commandments (v.7) and it was that which resulted in his "spiritual death."
In a commentary written by the faculty of Dallas Theological Seminary John A. Witmer writes,
"As a result Paul 'died' spiritually (cf. 6:23a) under the sentence of judgment by the Law he had broken...so this sin deceived him...and 'put' him 'to death' (lit., 'killed' him), not physically but spiritually" (The Bible Knowledge Commentary; New Testament [Colorado Springs: Chariot Victor Publishing, 1983], 467).
Paul could not die spiritually unless he was first alive spiritually. So he was alive spiritually when he emerged from the womb.