St. John recognized that this movement had some serious theological difficulties. He exposed these difficulties in relation to the Incarnation. He showed that, since Christ's human nature was real, and was the same as ours - "alike in all things but sin" - it was possible to depict the human nature in religious art. In other words, we not only can but should use the things God has given us to worship Him, from wood and stone up to Christ's own humanity. His deep arguments convinced people, and eventually overcame Iconoclasm. So it's in large part thanks to St. John of Damascus that our beautiful Cathedral here is full of such inspiring windows and statues.
But we should not think that Iconoclasm was only a problem in the Church a thousand years ago. It has continually popped up in history. For example, it surfaced again in the Reformation, especially in the denominations influenced by John Calvin, which even now tend to have little or no religious art [and for the same reason, a very shallow understanding of the sacraments - not said but relevant]. It's also one of the sources of our culture's willingness to disregard some people's full humanity. The Culture of Death is a form of iconoclasm, and the homosexual lobby is influenced in a similar way.
As we continue with this Holy Mass and into this season of Advent, there are two things we can do. First, we can deepen our faith, as we are always called to do, using the ways the Church offers us: for example, studying and praying with the Scriptures, reading the Catechism, listening to Catholic radio and reading the Fathers, all so readily available to us in this digital age. The more we know our faith, the closer we can be to Jesus Christ, and the more open to all of His gifts of grace and mercy. This is how we learn to love both God and neighbor, just as Pope Francis is constantly calling us to do.
Second, we can imitate St. John of Damascus in his witness and charity. We can show the world the quality of our love and faith by how we live. What we say and what we do each day conveys to everyone around us what we really value. Let us display the grace and mercy of Christ we have received, especially in what we are willing to tolerate - namely, the human weaknesses of our brothers and sisters, which is always redeemable - and in what we refuse to accept and condone - namely, the evils that are contrary to our faith. We can always make the distinction for our neighbor between weakness and evil, and be merciful without being indifferent, just as we pray God always is with us.
By growing in our faith and by the witness of our lives, we receive and share the coming salvation of our Lord Jesus Christ.
* Actually, I misspoke; he was a city counselor in Damascus, and left there about 730 to become a monk at St. Sabas's monastery near Jerusalem, and was ordained there.
** Icon from Russian Orthodox Cathedral of St. John the Baptist in Washington, DC: www.stjohndc.org