If Mary is conceived without sin as the Catholic Church teaches, then doesn't that mean that Mary does not need a savior? That seems to go against Christian doctrine that we all need Christ as our Savior, doesn't it?
That is a very common question and not one that is very easy to answer from a theological position. The best and most easiest explanation is through a modern day parable. Here it goes - There once was a road with a large and deep hole in it. The hole was so large that it could swallow up many, many people at the same time. The hole became muddy because of all the rain water that filtered through it. Men would walk down the road and invariably fall in, no matter what sort of warning signes were put up. They would be become muddy and wet and would often become injured. There was one man, Joshua, who could get people out of the whole and he would pull them out and clean them off.
One day Maria was walking down the road. Joshua saw her coming over the hill, threw himself over the hole and Maria walked right over it. Maria never became wet or muddy or injured.
So, you can probably tell who is who pretty easily in the story. The hole is the world with all of its tempations, attractions, and occaisions of sin. Joshua is Jesus. The people who fall in the hole are most of humanity. The mud and injuries represent the life of sin that most of us lead. Jesus saves us after we fall in the hole, dirty our souls, and become sinnners.
Maria, represents the Virigin Mary. Jesus saves her from the hole before she falls in. She never gets the stain of sin. So, although Mary was sinless, before her birth and through her whole life, she still needed Jesus as her savior. Jesus just saved her in a different way, before she sinned (or fell into the hole) unlike the rest of us who Jesus saved after we sinned.
I hope that this story helps explain it a little better.