You said it your self, she needed a Savior because she was a sinner.
The statement in Romans 3:23 here is short and to the point: Everyone sins. Everyone has sinned. There is no one who does not sin (
Romans 3:10). This further emphasizes the point Paul drew from Old Testament Scriptures earlier in this chapter. There is no escape from this label. Paul does not offer any category besides "sinner," and everyone falls into it. The previous verse emphasized that there is "no distinction." The most moral of humans—relatively speaking—and the most perverse of humans are all in the same container: "sinner."
Worse, knowing the difference between right and wrong, even the law given by God, doesn't make us moral. The Greek word translated as "fall short" here is in the present tense. In reality, we
keep on falling short. In other words, even knowing the consequences of our sinfulness is not enough to keep us from sinning (
Romans 1:18–20).
Because none of us are sinless, all of us fall short of God's glory. That matters, because we cannot be saved from God's angry judgment against our sin except by being sinless. That is God's standard, and we all fall short of His "glory" because of our sin. God's glory, or the glory of Himself and His kingdom, is what He shares with those who are in His family, His children. Our sin, though, keeps us from sharing in His glory.
Paul then continues in Romans 5 12Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all men, because all sinned
All people inherited sin from Adam and Eve, specifically from Adam. Sin is described in the Bible as transgression of the law of God (
1 John 3:4) and rebellion against God .
Genesis 3 describes Adam and Eve’s rebellion against God and His command. Because of Adam and Eve’s disobedience, sin has been an “inheritance” for all of their descendants.
Romans 5:12 tells us that, through Adam, sin entered the world and so death was passed on to all men because all have sinned. This passed-on sin is known as inherited sin. Just as we inherit physical characteristics from our parents, we inherit our sinful nature from Adam.
Adam and Eve were made in the image and likeness of God (
Genesis 1:26-27;
9:6). However, we are also in the image and likeness of Adam (
Genesis 5:3). When Adam fell into sin, the result was every one of his descendants also being “infected” with sin. David lamented this fact in one of his Psalms: “Surely I was sinful at birth, sinful from the time my mother conceived me” (
Psalm 51:5). This does not mean that his mother bore him illegitimately; rather, his mother had inherited a sin nature from her parents, and they from their parents, and so on. David inherited sin from his parents, just as we all do. Even if we live the best life possible, we are still sinners as a result of inherited sin.
Being born sinners results in the fact that we all sin. Notice the progression in
Romans 5:12: sin entered the world through Adam, death follows sin, death comes to all people, all people sin because they inherit sin from Adam. Because “all have sinned and fall short of the glory of God” (
Romans 3:23), we need a perfect, sinless sacrifice to wash away our sin, something we are powerless to do on our own. Thankfully, Jesus Christ is the Savior from sin! Our sin has been crucified on the cross of Jesus, and now “in Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace” (
Ephesians 1:7). God, in His infinite wisdom, has provided the remedy for the sin we inherit, and that remedy is available to everyone: “Therefore, my brothers, I want you to know that through Jesus the forgiveness of sins is proclaimed to you” (
Acts 13:38).
So yeah, even babies need a Savior. Jesus was without sin because He is God, born of the Holy Spirit. Mary is not. What the Catholic church teaches about Mary is disgusting (actually that's not Mary, that's an idol. I would not be surprised if Mary will be the first one to condemn you all for worshipping her.