My wife Elaine and I had the privilege of attending a special two-hour prayer service and Mass at St. Anthony Church in Everett a few days before and in anticipation of the Feast of the Annunciation, known also as the Solemnity of the Incarnation or the Conception of Christ. Organized by Sandi Arjune, a friend of and co-conspirator in faith-sharing with my wife, the event drew a church-full assembly of people. Before Mass we prayed the Rosary and the Divine Mercy Chaplet, with each decade led in different languages by individuals from different ethnic backgrounds. At the back of the program booklet handed out to us as we entered the church, Sandi included brief explanations of the various apparitions of Mary related to the dialects chosen for the prayer service. Glancing at these entries before the praying began, and then looking around me and noticing the variety of nationalities represented by other attendees, I was moved.

The experience made me think of an evocative reflection by Joseph Ratzinger in his 1968 catechetical work, "Introduction to Christianity," which uses the Apostles Creed to explain the Catholic faith. In his discussion of "I believe in Jesus Christ, His only Son, our Lord," then-Father Ratzinger likens the Incarnation to a genetic mutation that forever alters the make-up and destiny of humanity in its entirety, and thus of each human person. He writes: "Faith sees in Jesus the man in whom -- on the biological plane--the next evolutionary leap, as it were, has been accomplished."

Through the miracle of God becoming human in order to die for us, people of all nations were affected, acquiring the recombined gene, as it were, that fits us for entry into one new family. When I looked around at St. Anthony's and saw the wonderful array of faces, brought together by a common faith, the essence of the feast we were anticipating became manifest.

The Incarnation happened in a way that blessed human existence itself. God did not descend from the sky one morning, like an alien emerging from a flying saucer, to announce His presence. His Son assumed human nature, subjecting Himself to every process that biology directs to make us grow, and to every contingency that threatens that growth. He came and lived among us by entering into the means by which each of us exists, not from outside of humanity but from within.

Nor, however, did God declare His entry by sending out an ethereal mind-wave, a thought-email that popped into our cranial in-boxes. He instead became flesh, dwelling among us in a way that was complete from the smallest atom to the largest human organ, the skin. He was visible, touchable, audible, and mortal. He relied on the ordinariness of substance, of material being, with all obvious limits applying, to communicate eternal and divine love.

By doing so in the manner indicated, Jesus changed existence for all who exist as human beings. Whatever anthropology, the study of humanity, can conclude on its own about who we are, to that we must now add the data of the Incarnation.

As part of staff continuing-education, two of my colleagues at the Massachusetts Catholic Conference were sent recently to a week-long theology of the body retreat conducted by Christopher West. Kathy Magno and Kathy Davis (whose husband John also attended) went expecting to learn helpful information, and returned with more than just additional knowledge. They came back transformed. They saw, for the first time, the greater beauty of the Church's incarnational vision of human dignity. It was presented in a comprehensive, compelling manner, and they realized how much it applied to their own lives.

The Church's mission in the world of public policy touches on issues relevant to the theology of the body, and thus implicates the Incarnation, because human dignity is at stake. Our message must be conveyed in terms that anyone can appreciate, and so it must employ principles and concepts of common understanding. Yet to be missionaries of the Incarnation requires a spiritual grounding. We should be able to glimpse, and be moved by, the ultimate realities. Then we will want and have the courage and aptitude to propose realistic answers to such social challenges as war, abortion, disproportionate distribution of wealth, and the disintegration of the family.

God becoming human changed everything through a glorious mutation of humanity itself. The Feast of the Incarnation is everyone's feast, and invites all to see, in the face of neighbor and stranger alike, the attributes of a divinely ordained kinship. In our yes to others is echoed Mary's Yes to the angel.

Daniel Avila is the Associate Director for Policy and Research of the Massachusetts Catholic Conference.