Purity Defined,

As I reflect on the last week, I recalled a discussion I had with an intelligent young man I work with. We happenened to be discussing different aspects of our faith and Mary (Theotokos) came up. I stated that the Church declared her sin free only after enough naysayers had said otherwise.
"Sin free";" how can that be when the Bible says that every man has sinned " he quipped. I said she is not a man. But somehow that didn't wash, I asked that if God wanted to could he make someone sin free ? If he could have put enmity between the devil and the woman ? He said that he felt that maybe during pregnancy that Mary could have been sin free but not her whole life. The fact is she was sin free as the Church defined. She has always held that position but just recently defined it. She is purity in a definition and we should respect that . She didn't have to cooperate with God but she did. Through that cooperation our savior was born . God Blessed her and us