St. Peter explained it, as Acts 2 and 3 recount. St. Stephen also, as Acts 7 recounts. And St. Paul, too, as Acts 13 recounts–not to mention his own letters, preserved in the New Testament.
Explained what? How to understand history.
The ancient Israelites knew one very important thing, namely that Almighty God reigns over time and unfolds it according to His plan. Time, in other words, moves toward a goal.
Other ancient people also grasped this, and they joined the Jews in waiting for the fulfillment of history. The synagogues scattered around the Mediterranean Sea held Jews and non-Jews who acknowledged that the Almighty had indeed already revealed Himself to Moses, but that another, more powerful and conclusive revelation was yet to come.
The Apostles addressed the hope of these Jews and God-fearers with the decisive declaration: The Messiah has come, and He has consummated history by conquering death. We can see how everything that came before happened to help us to recognize and understand the Christ. Now the New Age has dawned, the age of grace and fulfillment. Eternity has touched history in such a way that we who live in time can look forward to eternal life.
2014 A.D. Anno Domini. Year of the Lord, our Lord.
Now, of course, every year since the very dawn of creation has belonged to the Lord, has been a year of the Lord.
But 2014 years ago, the Lord made the years His own in a new way. Or, maybe the better way to say it is: He made the years truly ours, in the sense that we can gather them up into the fulfillment of eternity, rather than just watch them fritter away towards oblivion.
Praise You, Jesus, for turning time itself into a doorway to God. Now we see why the Almighty Father started this whole thing in the first place. History leads not towards death, but towards life.