I think the real challenge of evangelization in the modern age is the reality that pretty much everyone has already heard of Jesus Christ — or, at least, they think they have.
To our 21st-century eyes, the angel who shared news of the birth of Jesus with the shepherds had an easy job. All he had to do was announce it.
Our baptism compels us to do the same — to announce the coming of Christ over and over again, always and everywhere. But our audience is not a group of illiterate shepherds in ancient Judea. Our audience is a world that has heard so much about Jesus they often claim weariness of his name. So how do we do it? If we walk into a crowd of strangers and tell them we want to talk about Jesus, their reaction will probably be either “I already know about Jesus, thanks,” or “I’ve heard of him, and based on the behavior of those who claim to follow him, I’m really not interested in hearing more.”
Because in the end, our very lives are how we “announce his salvation” in the present day. We announce it in our actions to strangers. We announce it in our treatment of people who have wronged us. We announce it in our interactions with those who disagree with us.
How long had the coming of the Messiah been foretold to the Israelites? So long that, no doubt, many of them despaired of his coming altogether. So, God had to give them a sign: “You will find an infant wrapped in swaddling clothes and lying in a manger."
Now we are the sign.
The world has heard of Christ by now. But have they all seen him? It’s our job to show them.