What does St. Paul mean by "the end of the ages" in Sunday's epistle (Lent 3C)? 

"Now these things happened to them as an example, and were written down for our instruction, upon whom the ends of the ages is come. (1 Cor. 10:11)

How can he say of the church 2,000 years ago that "the end of the ages" had come upon them? How can we say it?

If we interpret Scripture with sacramental and incarnational lenses we will understand this phrase to be a descriptor of the Eucharist that the Corinthian church was about to celebrate.

Remember that Paul's epistles were written to be read on Sunday morning as the baptized assembled for Eucharistic intimacy with their Lord. Remember, further, that this epistle was meant to serve as the chief part of the Liturgy of the Word, and that upon completion of the Liturgy of the Word the Liturgy of the Sacrament would follow.

And so we do not just obtain Eucharistic teaching from the last seven chapters of First Corinthians, but we are made privy to an actual liturgy in progress.

How is the "Lord's Supper" "the end of the ages?" Because every Eucharist is an "installment" or the Parousia, the Second Coming of Christ. Every Eucharist is what Arthur Just calls "realized eschatology," which means the same thing: the future realized today. Or as we pray in the Lord's Prayer, "give us tomorrow's bread today" (a more likely translation of "daily bread" (ton arton ton epiousion)

How is that possible? Because as the church celebrates Eucharist "installments" of both judgment and salvation are carried out in the world in real time. For Holy Communion is not just "gospel" but it is "law" too. In it Christ intervenes into the affairs of men bodily to judge sin and put it to death, and by the same Real Presence to give life to all who believe these words, "given and shed for you for the remission of sins."

And so we can say of the church's Eucharist that in it, "the end of the ages" is come upon us.