Did Mary Have to be Sinless to Carry the Messiah?

Thanks to some free advertising from RasorsKiss, Ed "What the" Heckman, of The Greatest Pursuits, found my response to Rand’s screed and tossed in his two cents. It’s an intelligent, thought-provoking response. Here’s a sample:

Is it unreasonable to think that if God/Jesus was in intimate contact with ‘sinners’ before the formal end of that separation then there would be no problem with intimate contact with Mary in spite of her own sins?

If anything, the Bible implies that it was necessary for Mary to be a sinner. Consider this passage in Galations:

But when the fulness of the time came, God sent forth His Son, born of a woman, born under the Law, in order that He might redeem those who were under the Law, that we might receive the adoption as sons.

(Gal. 4:4-5, NASB)

I’m not sure when I’ll have time to respond, so I hope some of my readers will help me out.