The Bible says for the wages of sin is death. If you claim that babies are not born sinners why do babies die?
"Do you not know that when you present yourselves to someone as slaves for obedience, you are slaves of the one whom you obey, either of sin resulting in death, or of obedience resulting in righteousness? But thanks be to God that though you were slaves of sin, you became obedient from the heart to that form of teaching to which you were committed, and having been freed from sin, you became slaves of righteousness. I am speaking in human terms because of the weakness of your flesh. For just as you presented your members as slaves to impurity and to lawlessness, resulting in further lawlessness, so now present your members as slaves to righteousness, resulting in sanctification. For when you were slaves of sin, you were free in regard to righteousness. Therefore what benefit were you then deriving from the things of which you are now ashamed? For the outcome of those things is death. But now having been freed from sin and enslaved to God, you derive your benefit, resulting in sanctification, and the outcome, eternal life. For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord" (Romans 6:16-23).
In Romans 6:23, Paul was using the illustration of slavery. When you work as a slave for sin, you earn the wages of death. When you work as a slave for God, you earn the wages of eternal life. The latter is a spiritual concept. You are physically alive when you work as a slave for God, so we are not earning physical life -- we are talking about spiritual life. Thus, the death discussed that is being paralleled to life is also spiritual.
Yes, because of sin, physical death did enter the world, but that is not what is being discussed in this particular passage. "For since by a man came death, by a man also came the resurrection of the dead. For as in Adam all die, so also in Christ all will be made alive" (I Corinthians 15:21-22).
Every person conceived in this world has left it through physical death. That includes Jesus, who had no sin. Therefore, death does not tell us whether a person was righteous or wicked. The death of a child does not tell us whether the child had sinned or not.
"Truly, this only I have found: that God made man upright, but they have sought out many schemes" (Ecclesiastes 7:29).
Thus, we learn that people are born sinless, but become sinful as they grow up. This truth is further emphasized by Ezekiel 18. In the first part of the chapter, God shows that sin is an individual's responsibility. He summarizes His points by stating, "The soul who sins shall die. The son shall not bear the guilt of the father, nor the father bear the guilt of the son. The righteousness of the righteous shall be upon himself, and the wickedness of the wicked shall be upon himself" (Ezekiel 18:20). Since a son cannot inherit the guilt of his father, Adam's children did not inherit the guilt of Adam. Sin is not passed on genetically.
The root problem is that there is a denial of what is sin. "Whoever commits sin also commits lawlessness, and sin is lawlessness" (I John 3:4). Sinfulness is a state reached when an individual breaks a command of God. A baby has not done anything yet, and so is not guilty of breaking a law of God.