I began by pointing out something that might seem odd: Advent has begun, we're all thinking about the coming of Christmas, and yet the readings at Mass had nothing (directly) about the birth of the Lord. Instead, all the focus is on the Lord's coming at the end of time. Why might that be?
My answer was that each "coming" only makes sense in the light of the other. We needed Christ to come at Christmas in order for a happy outcome at his final coming. We celebrate his coming at Christmas because of our hope in his his final coming. Or words to that effect.
I also explained how when we say Christ will come again, we don't mean he left. I said something like, when I came over here for Mass, I left my house. As far as I know, I'm not there now! But when the Lord returned to heaven, he nonetheless remained here. So when we speak of his return, what we mean is that he will be here in the fullest sense.
I cited the example of the mountain in the first reading: being the highest, lifting up the house of God and drawing all to it. Has that happened yet? No; but it will happen.
From there I explored the mystery of how God involves us in his work. Christ could do it all on his own; he doesn't need us (in the strict sense); yet he chooses to make us part of his work. So the coming of his Kingdom involves us. We are his instruments to build up that mountain and draw all the world to God's house. We are the invitations people receive: our lives, with God's word written in them, are the invitation people need. Our goal, of course, is to be invitations that actually invite, rather than not.
Somewhere in here (I gave this homily four times, and it changed each time) I talked about the Lord's message of being awake. The message is for those who aren't awake; if we're seeking the Lord, looking for him, we're awake. So the question for us is, are we "awake"? I.e., are we aware of his presence, aware of his action in our lives?
I gave examples from my own circumstances: days when I get so busy I barely pray--"does it surprise you that that can happen to a priest? It does; has it happened to you?" And I talked about how I've prayed for God to help me in a difficult situation, only to have the situation go so smoothly, I actually forgot about what I'd asked for, only to realize it days later: that problem that I was so concerned about never happened--and I never said thank you to God for such an excellent answer to prayer!
I gave the example of our 24/7 Perpetual Exposition chapel--another way Christ is present among us, but are we awake to it? I talked about the sacrament of confession. I said, suppose I told you we had vending machines in the back of church, with a pill to regrow hair, or a pill to make us svelte--and the pills were free! How popular they would be! But we don't have that; instead we have the sacrament (I was gesturing to the confessionals) that dispenses mercy, forgiveness, reconciliation and peace...for free! Are we awake to Christ in our midst?
And I came back to the Mass as Christ's supreme presence--the Cross made present, an explosion of grace flowing to us from the Mass, and the Eucharist. Our being awake, being open, means we change; and we become better instruments and vessels of what he is doing in our world: getting the mountain built, and getting everyone to his house. That's our job.
Anyone who heard me deliver the homily, feel free to comment or let me know if my recollection is faulty!