This feast of the Immaculate Conception is the day set aside for thanking the Father for making Mary completely loving and lovable, and for thanking the Son for giving Mary to us as our mother.
I don’t think we are to be thinking of Adam’s sin staining every child conceived.
For one thing, Pope John Paul II told us there is no such place as Limbo where unbaptized infants are for ever shut away fro God’s presence. He said the existence of such detention goes against what we know of God’s infinite mercy.
For another thing, Vatican II clearly stated that from the first moment our existence we receive an invitation from God to converse with him. Here is paragraph 19 of the Constitution on the Church in the Modern World.
The dignity of man rests above all on the fact that he is called to communion
with God. The invitation to commune with God is addressed to him as soon
as he comes into being.
There is nothing about Original Sin in the Bible. The first use of the term came from St. Augustine around the year 400. There were people then who were saying we have the inborn ability to make ourselves perfect. Against that St. Augustine quoted St. Paul when he said, “I take delight in the law of God in my inner self, but I see in my members another principle at war with the law of my mind, taking my captive in law of the sin that dwells in my members.”
By that other principle that Augustine then called original sin it is likely that they both had in mind our hereditary weaknesses. The following Christian generations that believed in Adam and Eve as historical persons, took Augustan’s term of “Original Sin” to be a black mark on the soul that could only be washed off by the Sacrament of Baptism.
By the Immaculate Conception we look on Mary as the one person who never fell prey to hereditary inclinations toward evil.