When I converted to Catholicism in my mid-30s, the man who brought me to the faith was David Carucci, a ruddy-faced priest only a little older than me, with dark curly hair and a scruff of beard. My wife and I had begun attending Mass more regularly after our children were born, even though as a lapsed Baptist, church was not my favorite place to be. But Father Carucci’s dry, self-deprecating humor and the running nobody’s-perfect message in his homilies, combined with the beautiful formality of the Mass, reeled me in.

Among my favorites from Father Carucci’s messages was something he once said about light. I can’t remember the date, or even what liturgical season we were in, but in the homily, Father Carucci reminded us that light always conquers darkness. If you come home at night and turn on a lamp, the darkness could never push the light back into the bulb. Likewise, even a tiny flame flicking on the wick of a small candle overcomes a bit of the darkness around it. This message of hope was, for me, the eureka moment. He was right: light does always conquer darkness.

Whether we’re talking about a homily by a Catholic priest on an otherwise ordinary Sunday or something much more far-reaching, like the hymn made famous by Civil Rights activist Fannie Lou Hamer, “This Little Light of Mine,” the realization that light always conquers darkness is now at the root of my faith. I had never thought of it before that day, and I have not forgotten it since. That simple fact of the physical world is evidence of God’s superiority to all of the things that we regard as bad or wrong or evil. Each morning, the light from the Sun ends the night, and when night comes again, it is only because the source of light shifts in space, not because the darkness turned the tide in its favor.

Today, Christmas Day, is a day of light. It is the day that we set aside to celebrate the fact that the Son of God came to Earth to live his thirty-three years of life among ordinary people who misunderstood him, mistrusted him, and ultimately betrayed him. But light always conquers darkness, and though the people in Jesus’ life may have mistreated and abandoned him, the one thing they could not do was forget him. His light came into the world, and it can’t be extinguished or overpowered.

I hear sometimes, even in homilies in Catholic Masses, that the world is at war with Christianity and that secularism and subjectivity are beating back the ultimate truths of our faith. Maybe. But rather than harp on what I can’t control or change, and rather than assign motives to people I don’t know, I choose to root my thought and actions in Father Carucci’s inauspicious statement made on an inauspicious Sunday: the darkness will never conquer the light. Never.