Thank you for the question, although I wish to state up front that I am not the be-all end-all when it comes to all things Christian. I also want to make it clear that I am not an expert on Catholicism, so I can only express my views, and not church dogma.
When sin entered the world, man had a choice to make. God was the ruler of this world as long as man chose to follow His will. When man partook of the fruit of the Tree of Knowledge of Good and Evil, he made a symbolic choice of Satan as his new leader. It was a sin to partake of that tree. The wages of sin were death.
God could have allowed man to be forever condemned to the wages of his sin. But God sought to redeem man. Only through the ultimate sacrifice could man's soul be purchased back from Satan. From the moment man/woman partook of the apple, Satan's law ruled this world. At the Cross, Jesus sacrificed His life to purchase our souls back.
The wages of sin was death. To keep man from having to die for all of eternity, Jesus died a perfect sacrifice for our imperfect lives. At that moment man again had a choice. He no longer had to face an eternal death. If he would accept God's leadership and avoid the forbidden fruit (sin), he could be assured of eternal life.
Jesus immaculate conception was important. It was important that we realize the Son of God came down to redeem us. Although He was born as a man, it was a seminal event. He was not just any man. Our fate did hang in the balance. Jesus had to face the very same temptations we do. Through all of it He prevailed. We were redeemed.
A part of the Holy Trinity died on that cross. A Being with the power to command the forces of nature, walk on water and raise men from the dead, submitted Himself to the ultimate humility at the cross. He died when He could have killed, by any means imaginable, those who ordered or facilitated His death.
Was it important that Jesus was an immaculate conception? Yes. Is it important that Satan demising the sacrifice, and it's significance? Yes. Satan will do anything in his power to discount what it was that Jesus did for us. His ability to confuse and destroy is all that he has left. And even that is only temporary now. Out of all the universe and other worlds, we were the only one's to give Satan a home. We were the only ones to chose his rule over God's. That rule has ended. But it's effects are still being felt.
He has no power over us as long as we accept Christ's perfect death as an atonement for our sins. But we must accept it. It cannot be forced on us. Redemption requires acceptance and a changed life on our part. God can NOT force salvation on us any more than he could force it on Adam and Eve. They had a choice. We have the SAME choice. Will we be perfect? No. Must we try? Yes. Will we earn our salvation? No. But we will have to try to live as God would have us live. He has paid the price for our sin, but he is not going to allow us to do everything bad that we can imagine, then save us to live that life in heaven. We should be conducting ourselves on this earth as if we were already in heaven. Repentance is necessary before salvation can be claimed. Adam and Eve made a grave mistake, but they were repentant. I have no doubt they tried to live good lives after their sin.
You refereed to the Catholic church as being the entity that placed significance on the immaculate conception of Christ. I believe you are referring to the deification of Mary, Jesus mother. My religion teaches that Mary was a good woman honored of God. It does not attribute God-like status to Mary, or impart a holy position for her. She was the woman honored above all others in that she carried the baby Jesus to term, delivered Him and raised Him. I believe that is all.
Obviously I respect Mary for her role. God obviously thought very highly of her. But if you'll take note, Jesus rebuked Mary at times saying He must be about His Father's business. If Mary had truly been deified, I don't think that would have been necessary.
God the Father, Jesus His Son and the Holy Spirit are one. They are joined. Things changed when Jesus took the form of a man. I am convinced that Jesus was forever changed, a constant reminder of Sin throughout the ages. His heavenly body was left behind. His human body took it's place.
Do I have all the answers? No. Am I absolutely sure what I have said here is right? No. It's about the best I can do until I get to ask the pointed questions from the only person who can explain it all to us. Realizing our limited concepts regarding life, death and one's soul, it's going to be hard for us to take it all in even when He explains it.
There, my neck is out. Whack away fellow Freepers. Grin.
The Bible teaches that Mary was "full of grace" (the literal meaning of the angel's greeting to her) and she herself, under inspiration, said "all generations to come shall call me blessed".
That's a bit more than just a "good woman honored of God". Sarah was a "good woman honored of God," but nobody ever said anything like that about her.
She's not a goddess, she's a redeemed and glorified human being. She's "deified" in the sense that all the glorified are "deified": they are made partakers of the divine nature, see 2 Pt 1:4. Religions which teach more than that are idolatrous; religions which teach less than that contradict Scripture.