Benedict XVI:

"... With regard to the embryo in the womb, science itself highlights its autonomy capable of interaction with the mother, the coordination of biological processes, the continuity of development, the growing complexity of the organism. This is not an accumulation of biological material, but a new living being, dynamic and wonderfully ordered, a new unique human being. So was Jesus in Mary's womb, so it was for all of us in our mother’s womb…there is no reason not to consider him a person from conception."

(via Rorate Caeli)

The Feast of the Annunciation -- the Church's proof that the soul is infused at conception? Except this is not what the Holy Father seems to be saying here, just that contemporary embryology maintains that human life begins at conception. Nothing about the infusion of the rational soul.

Theology may not be necessary for the salvation of an individual, but as a form of acquired wisdom, it is indispensable for those who are charged with instructing others (bishops and priests). While a Christian witness may lead others to Christ, in this providential order it is not sufficient for the conversion of all. A role has been given to some of us to lead others to Christ through words, and not just deeds.

The application of human reason to [understanding and relating] the truths of the faith can be considered theology. But if our ability to reason about Faith admits of different degrees of excellence, and can be perfected through an intellectual habit, then we should not reject outright the claim that theology is a science (as understood by Aristotle).