When we are to understand a specific subject in Scripture, we cannot pick and choose passages to form our understanding. Such would make us unscriptural in our belief. Rather, if we are to stay true to the Word of God, we are to take God's words in their entirety, as they are, unadulterated by our opinions, perspectives, wishes, and desires. This is especially true when we come to the subject of man's sinfulness.
If Scripture speaks of man being dead in sin (Eph. 2:1), unable to perform any works of righteousness, and then speaks of this same man in various situations performing some good works, do we run with the second scenario, rejecting the first? Do we conclude that because man performs some good works, he is not entirely dead? No. To fully understand the subject, we must grab hold of the furthest conclusion (man is dead in sin) and work our way to a complete understanding from there.
Sin can so deceive us into believing that its existence is less of a problem than it actually is. It blinds our eyes to the reality of Scripture's teaching. Just as the sun still shines, though the blind do not perceive it, God's Word regarding sin is true, even if we don't believe it.
When Paul calls all men dead in sin, he understands the metaphor he is using. If he didn’t, he would have no understanding of Christ's death, seeing as he uses the metaphor in the same passages he extols Christ's death. There is a reason for his using the metaphor of death: sin is eternally deadly. Sin not only brings death but has us in its grip from birth.
Furthermore, being dead in sin is not an idea Paul came up with. He got it from the Old Testament. When David repents of his sin, he stops himself from blaming God for it and places the blame completely on himself. "Behold, I was brought forth in iniquity, and in sin did my mother conceive me" (Ps. 51:5). In another place, he points out the sin of the wicked with similar words. "The wicked are estranged from the womb; they go astray from birth, speaking lies" (Ps. 58:3). Before the Jews could turn this into an us-against-them argument, Paul reminds them, "For we have already charged that all, both Jews and Greeks, are under sin, as it is written: 'None is righteous, no, not one; no one understands; no one seeks for God'" (Rom. 3:9-11). Whom was he quoting? It was King David and the prophet Isaiah.
There is one passage that rises above the rest to display this reality. In Romans 5, Paul takes the readers back to the conception of sin.
"Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned— for sin indeed was in the world before the law was given, but sin is not counted where there is no law." (Rom. 5:12-13)
We are all born with a sin nature because we are born of Adam. Adam, as our federal head, represents the whole of humanity in his sin. We inherit this sinfulness, from which we act sinfully. If you ever wonder why the human race cannot get rid of sin and create a legacy of sinlessness, it is because we are born with the nature to sin. It is clear that if we are born of Adam, we are under sin’s domination.
Not only does Paul explicitly explain this in the passage, but a holistic understanding of the rest of the gospel bears witness to this truth. Why did Christ have to be born of a virgin, conceived of the Holy Spirit? Why must we be born again? Why is the whole work of salvation from God (Eph. 2:8-9)?
The whole of Scripture bears witness to the reality that Adam’s sin has been passed down generation to generation, and will continue to the end. Therefore, we cannot claim a lesser view of sin. To do so would be to disregard Scripture, and plunge ourselves into ideas inconsistent with reality. Man being dead in sin is the Christian’s basic understanding of sin.