Romans 5:12 Passed upon dieelthen (NT:1317) ef' (NT:1884). Literally, "came throughout upon." The preposition dia (NT:1211) denotes "spreading, propagation," as eis (NT:1500) "into" denoted "entrance."

(from Vincent's Word Studies of the New Testament).

Romans 5:18 - 19 says, “through one man’s trespass, judgment came to all men, for by one man’s disobedience all were made sinners.” This Scripture clearly shows sin is inherited through Adam’s disobedience, not ours. According to Rom.5 If one man (Adam) made us all sinners, it is also by one man (Jesus Christ) that can make us all righteous (those who believe). While we did not have a choice with sin -- we do have a choice to be in right standing with God through the righteousness of Christ and have the power to restrain from sin.

If one takes the position that we are not born sinners but only sin takes place by a choice then it means that everyone is born innocent (perfect), just like Jesus, without ever having a virgin birth. Paul writes that Sin entered the world through one man (Rom. 5:12-21), Adam. The term Original sin means Adam losing his original righteousness he was made with and passing it on to his offspring.

Paul’s point is that Adam’s sin was a single representative act for all his posterity, which is now reckoned to their account having sinned in him. Adam, as the first man was the natural headship of the human race. From him flows man’s fallen nature, passed on through reproduction. The sin nature affects the immaterial part of man, which is expressed by our outward actions. We sin because we have the nature of sin in us.

It is not just our physical actions that make us a sinner, but our mind is affected also. Sin shows its outworkings through our actions (Ps. 58; Job 15:14, 25:4; Eph. 2:3; Rom. 5:12-19), though we cannot see sin express itself all the time, it is still there waiting to be alive. Like a piece of firewood ready to be kindled by a small flame.

James explains how sin is birthed. Jm.1:14-15 “but each one is tempted when, by his own evil desire, he is dragged away and enticed. Then, after desire has conceived, it gives birth to sin; and sin, when it is full-grown, gives birth to death.” The source of sin doesn’t come from the outside but from within, it is the temptation to sin that comes from outside and brings life to what is already there. We are drawn away from our own desires (the Greek means to be lured into a trap). It is not a single act, but a process that begins in our heart.

This sin nature is the basis for all sinful acts and habits, everything we do wrong. Many times we treat the symptoms but not the cause. King David claimed he was conceived in iniquity (Ps. 51:5). Meaning even he was not exempt from the inheritance of sin, it was there from the beginning of his life in the womb.