As a former Protestant (agnostic for 25 years, Protestant for 4, Catholic for 1), I had huge problems with anything relating to Mary. I still have resistance about her (e.g., why pray to anybody else when I have the freedom to pray directly to any person of the Trinity?), but I look forward to getting to know her better.
Why do Protestants have a problem with all things Mary? I think that individual Protestants will not have very solid answers because I think the real problem stems from the Protestant Reformation. The rebellion against Catholicism is so strong that anything that seems uniquely Catholic (Mary) has to be thrown out. Also, the great majority of Protestants truly do think Catholics worship Mary, which is (and should be) abhorrant to them. In fact, too many Catholics think Catholics worship Mary! In my one short year of being Catholic, I have already had numerous experiences of Catholics admitting to “worshipping” Mary or stating that Jesus’ divinity comes from His mother Mary or stating that Mary herself is divine (even one woman who said Mary is part of the Trinity). We cannot expect Protestants to understand the proper devotion (hyperdulia) given to Mary if so many Catholics do not understand.
I noticed, even as a Protestant, that when studies on “women of the Bible” were completed, Mary was virtually ignored. Mary might be mentioned as a nice, upstanding lady in passing, then the teachers would spend lots of time on women of the Bible who were mentioned only briefly (like the prostitute who hid the spies and, as a result, was saved when the city was destroyed). I would like to ask individual Protestants what they think of the mother of Jesus (don’t say “mother of God” to them!) is ignored in comparison to other women of the Bible. Even if all of the Catholic teachings are not true (immaculate conception, perpetual virginity, assumption), shouldn’t Mary receive much attention and respect?
I understand that it is fitting, but not necessary, that Mary remained sinless. I also was taught a very helpful way to think of her sinlessness: ALL who are sanctified (saved) are sanctified through Jesus. There is only one door to the Father and that is through Jesus. However, not all have been saved in the same manner. One can be saved from a mud pit in two ways: The person can fall into the mud pit and be pulled out by the rescuer, OR the rescuer can shout out ahead of time, “Look out! A mud pit!” and push the person to safety. Those folks who find themselves in purgatory or heaven were saved the first way, but Mary was kept sinless the second way. God is outside of time, so He was able to keep Mary sinless ahead of time through the Redeemer who came after her own conception. This is my understanding, so any errors are mine, not my catechist’s.
Here is a question I still have about Mary: If she was kept sinless by God, why does she deserve so much respect for her fiat? If you were sinless, wouldn’t you do all of God’s will easily as well? If somebody gave you the gift of sinlessness, wouldn’t obeying be extremely easy? I do not ask this question to be disrespectful but out of sincere confusion.