The Catechism tells us that the Mass is called the Mass “because the liturgy in which the mystery of salvation is accomplished concludes with the sending forth (missio) of the faithful, so that they may fulfill God’s will in their daily lives.”
We English speakers may not quite get the force of that due to the crummy translation of the Mass in the American Church—a translation that vitiates the force of the actual words of the liturgy, apparently due to the theory that we are too dim or dumb to cope with it. (Did you ever notice that the same people who say that Americans are bold and independent thinkers who don’t need the Church to guide them in their moral lives are the ones who seem to believe that Americans are helpless mewling children who could not cope with a translation of the Mass that, like, actually translates what the Latin says and doesn’t replace it with dumbed-down drivel?)
But I digress. My point here is this: the actual Latin text of the Mass does not conclude, “The Mass is ended, go in peace.” It concludes “Ite, Missa est” which is much better translated as something like, “Go! You are sent!” “Missa” is the root, not only of “Mass”, but of “mission” and “missionary”.
Now, “Go! You are sent!” is a radically different statement than “The Mass is ended, go in peace.” The former has the sound of a trumpet in it. It’s a clarion call to bring Christ to the whole world, to cast down the mighty in their arrogance and lift up the meek and lowly. It’s the sort of thing the apostle Paul could (and in fact did) hear from the mouth of the Risen Christ! It’s the sort of ringing call to get going and get out there to save the world that the apostles heard from the Risen Lord in Matthew 28. In contrast, “The Mass is ended, go in peace” is not a translation, not even a paraphrase, of what the text actually says. Indeed, it is an astoundingly weak tea replacement of the words of the Mass with some sentiment of a translator with a tin ear, especially when followed by “Thanks be to God!” Talk about a prayer that goes “clunk”! It conveys a sentiment more like “Well, Mass is finally over [Thanks be to God!]. Go home and watch some TV”. It calls us nowhere and bids us do no more than drift out of the sanctuary toward nothing in particular. It’s like translating, “Veni, Vidi, Vici” as “I visited France. I saw a lot of interesting things. I decided live there as an important official in the Italian Ministry of Peacekeeping for Indigenous Peoples.”
The reason the Mass ends on this note of adventurous Mission is that Mission is, in fact, what we are called to through our Baptism and Confirmation. What we have received at the altar is nothing less than Jesus Christ himself, fully and substantially present in the Eucharist. And we have received him precisely so that we can turn around and walk out the door of our Church as a army of healers, peacemakers, lovers, and even martyrs,—all empowered by the Holy Spirit to assault the gates of Hell, liberate the captive, break chains, restore sight to the blind, give hearing to the deaf and a tongue to the mute. We have a mission and we have the supernatural power to carry it out! That’s what “Ite, missa est” means. It is shorthand for
“All authority in heaven and on earth has been given to me. Go therefore and make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you; and lo, I am with you always, to the close of the age.” (Matthew 28:18-20)
In other words, for the vast majority of us, the work of the gospel is to be done in the world, not in the sanctuary. At the altar, the priest presides because it is his task to hand on the Tradition and the sacraments to us. But in the world, we laypeople preside because it is our task to teach, sanctify and govern the world with the authority and power of Christ. In short, we laypeople have an office and we are sent to fulfill that office by the same Spirit of Christ who sent the apostles. We are not just schlepping out the door to kill time till it’s time to go to Mass again. We are sent. God’s word to us at the end of every Mass is “Go! You are sent!”