You owe a debt of gratitude to the Catholic Church which gave you that Bible.
Let's begin with your first statement: I was taught as a Catholic... that Mary is Christ’s co-redemptrix, and that she is actually the woman who would crush the serpent’s head and save the world
Jesus is the one Mediator of our salvation, our only Saviour. But He is not our only intercessor, as the following passage clearly indicates.
"I urge then, first of all, that requests, prayers, intercession and thanksgiving be made for everyone - for kings, for all those in authority, that we may lead a quiet and peaceful life in all godliness and holiness. This is good and pleases God our Saviour, who wants all men to be saved and come to the knowledge of the truth. For there is one God and one mediator between God and men, the man, Christ Jesus."
1Timothy 2:1-5
From this passage we can see three important things:
1. Paul is asking fellow Christians to pray and intercede with God for those in authority and for other third parties.
2. These prayers and intercessions are being made on behalf of other people, and to God. This is a mediation of prayer. Christians are being asked to mediate between all people, Christian and non-Christian, and God.
3. Since this is all one passage, it is absolutely clear that when Paul refers to there being only one mediator between God and men, he is not referring to the mediation of prayer. Jesus's unique mediation is a different mediation - the mediation of our salvation.
Jesus is the one Mediator of our salvation, our only Saviour. But He is not our only intercessor, as the whole passage above clearly indicates.
And we were also taught that Mary was sinless,
You are referring to the Immaculate Conception which states that the Virgin Mary was preserved free of Original Sin from the moment of her conception, and so was made sinless.
It has to do with the Holiness of God. God cannot tolerate Sin. Mary as the God-bearer in Jesus had to be sinless in order to be in such close proximity to God Himself. The whole Bible teaches that God's presence demands and imparts holiness. (Ex 3:5; Deut 23:14; 1 Cor 3:17; 1 Jn 3:5-6; Rev 21:27). The Jewish high priest entered the Holy of Holies only once a year, under threat of death if God's instructions were violated (Lev 16:2-4,13). The Ark itself was so holy that only a few were allowed to touch it (Num 4:15; 2 Sam 6:2-7). Thus, Mary, due to her physical and spiritual relationship with God, necessarily had to be granted the grace of sinlessness.
In other words, since Jesus took flesh in and from Mary's body, and also obtained His Human Nature from Her, she had to be perfectly sinless. The only question that then arises is when and how Mary was made sinless. Protestants are quite willing to admit that we are cleansed of our sins at baptism. Yet Mary could not have been baptised at the time of the Annunciation, or even Jesus's birth. For this reason her sinlessness had to come in a special and unique manner. To be pure and free from all sin as God required, she had not only to be free of sin at one point in time, (as one is immediately after baptism,) but to remain sinless throughout her life.
Luke 1.46: And Mary said "My soul glorifies the Lord 47 and my spirit rejoices in God my Saviour,"
We have seen that Mary needed to be perfectly sinless in order to bear Jesus. Did she attain that sinlessness through her own human efforts? No. She was redeemed by her son - as was all the rest of humanity. She needed God's Grace. And in order to be, and remain, sinless she needed that grace before her own birth.
We can see that in Luke 1.46 Mary speaks of God as her Saviour, but she speaks in the present tense. She does not say "God, who will be my Saviour." She has already been redeemed. If we look at one of the Old Testament passages that Mary bases her words upon, we see this more clearly.
Isaiah 51.10 I will greatly rejoice in the Lord, my soul shall exult in my God; for he has clothed me with the garments of salvation, he has covered me with the robe of righteousness, as a bridegroom decks himself with a garland, and as a bride adorns herself with her jewels.
As virtually every educated 1st Century Jew would have recognised, in echoing this passage, Mary clearly considered that God had already clothed her with the garments of salvation, and covered her with the robe of righteousness. Her sin had already been wiped away. This is supported by the angel's greeting to Mary:
Luke 1.28: The angel went to her and said, "Hail, you who are full of grace (Literally: you who have been and remain filled with Grace). The Lord is with you."
I would respectfully ask where Jesus or his apostles say we should ask or need those who have passed away to intercede for us?
It has to do with the Holiness of God. God cannot tolerate Sin. Mary as the God-bearer in Jesus had to be sinless in order to be in such close proximity to God Himself.
I've never heard this before and it isn't mentioned anywhere in the New Testament.
The holiness of God is precisely why we need Jesus so badly. Also, it doesn't sound as though Christ required that he have a perfect mother:
Your attitude should be the same as that of Christ Jesus: Who, being in very nature God, did not consider equality with God something to be grasped, but made himself nothing, taking the very nature of a servant, being made in human likeness. And being found in appearance as a man, he humbled himself and became obedient to death—even death on a cross! Therefore God exalted him to the highest place and gave him the name that is above every name, that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, and every tongue confess that Jesus Christ is Lord, to the glory of God the Father.(Phillipians 2:5-11)
The genealogy of Jesus in Matthew 1 includes some notable sinners -- such as Rahab the protstitute and the situation with David and Uriah's wife. Obviously this is Joseph's side of the family, but I think it shows that Jesus did not come from a sinless line of folks.
Protestants are quite willing to admit that we are cleansed of our sins at baptism.
We are free from the penalty for our sins because we have trusted in Christ's atonement, but we are not going to be sinless until we are fully sanctified when we get to Heaven. Paul talks about his sinful nature all the time.
When we accept Christ's salvation, we are overjoyed that Christ has clothed us with His righteousness and covered over our sins. God sees His Son when He looks at us, and Christ's righteousness, not our own, is what saves us. Mary was and is indeed a very special and blessed woman. God found favor in her -- amazing. But her song in Luke 46 is meant to glorify only the Lord. I am not sure how it is honoring to Mary not to do the exact same thing and rejoice along with her, and worship the Lord in spirit and in truth.
Sorry, I don’t owe any debt to the Catholic church. Your statement reminded me of the huge arrogance of the church I observed years before. If anything, they owe me for nearly destroying me, but through the grace of God I was able to survive and move beyond to salvation. I don’t owe the Catholic church anything. My gratitude goes to the Lord and Holy Spirit, who is the true living Word. And one way I’ll express my gratitude by serving the Body of Christ, which does include some members of the Catholic church.
I appreciate your attempt to explain, and the Word is good. And yes I ask others to pray for me, but I’m not going to pray for hours to saints asking them to intercede for me if I can’t ask them directly if they are no longer living on Earth. But I do know Jesus hears my prayers. So why would I pray to Mary to pray for me when she’s sleeping in Christ? I don’t believe she ascended into heaven or was free from original sin aside from the grace of God, that is not biblical. But as shown in the scripture you posted, yes she was sinless—redeemed—by the grace of God, in the same manner we all are. None of us are going to make it past judgement without the cleansing blood of the Savior.
I owe my allegience to the Lord who is the Word. And through the word I know that Jesus Christ is THE ONLY redeemer. I will never bow down or pray to Mary again, although I now understand her blessed role as obedient honorable servant who is now sleeping in Christ. The Lord has a special place for her, I know, but that does not mean we worship her. Yes her sins were washed away by the grace of God and the blood of Jesus, just as Christ did for all who are saved.
The focus belongs on Jesus the Savior, not on any one of his saints. I don’t know if this is typical, but every church I was involved with focused on Mary, even down to the name of the parish. No wonder so many bad things happened.