The Christian time-line of the age of the world changed only slightly in 1582, when astronomers determined the way to improve the calendar. At the Council of Nicea in 325 A.D.,  the Church fixed the Solemnity of the Resurrection to correspond with the Vernal Equinox. Historically, the Resurrection of Christ actually did occur almost simultaneously at the time of the Vernal Equinox. Though the Julian calendar, was very accurate, it became annoying to the Catholic Church because it caused the Solemnity of the Resurrection to keep moving further and further into the summer. The changes enforced by the Pope Gregory XIII in 1582, enabled the Church to consistently fix the precise day of the vernal, and autumnal equinox, (the two times during the year when the sun crosses the celestial equator, and when the length of day and night are equal). The older Julian calendar was unable to fix the days of Equinox. This problem was also annoying to scientists and agriculturists, who intended for men to know exactly when to plan to plant crops at optimal times. 

The most recent accounting of the age of the world according to Catholic tradition is over 400 old at this point, though it's present form is still almost exactly what it was 1000 years ago. As it is presented below, it reflects the latest change to the Calendar made by Pope Gregory XIII in 1582 AD. 

This reading has been incorporated into the Liturgy of the Christmas Mass for many, many centuries. It is customary for this to be publicly read from the pulpit, before the beginning of midnight mass on the Solemnity of Christmas. The reading can be found in any complete Roman Missal, (also called: The Sacramentary), under the section of readings for Christmas. 

This age of the world, according to the tradition of the Catholic Church, does not in any way conflict with modern science. Scientific evidence is overwhelming that the the universe itself is about fourteen billion years old. From the perspective of the ancients, however, God created the heavens and the earth within days of the special creation of Adam and Eve. It is most likely that the beginning of this calendar corresponds with the actual completion of God's work of the creation of the heavens and the earth in so far as they were finally prepared in readiness as the earthly paradise for man - complete with all animals, etc. Adam and Eve then, came into being soon after this final completion of God's creation of the heavens and the earth, by a miraculous act of special creation. All of the dates given in the reading below correspond precisely to all available historical data - including the approximate date of the great flood, according to Velikovsky and other scientists who accept the cataclysmic theories of the sudden extinction of the dinosaurs - and those theories which offer reasonable explanations about why creatures as mammoths were found millennia later in Siberia - perfectly preserved, frozen in glaciers - with their trunks actually still encircling the fruit of a tree from which they had been eating. These creatures had been frozen so suddenly, and their bodies preserved so perfectly - that their flesh was indeed eaten by those who discovered them.

There are absolutely NO historical documents in existence that suggest that men inhabited the earth before 5000 B.C. The most ancient hieroglyphics do not predate the year 3200 B.C. The earliest implementation and use of an alphabet corresponds almost precisely to the original documents of the Hebrew Pentateuch, which date from the year 1200 BC. The ancient Babylonians had written The Epich of Gilgamesh on clay tablets before year 1200 B.C., but there have never been more than bits and pieces of those tablets found. The oldest known complete narrative of the ancient Epich of Gilgamesh dates from no earlier than 600 B.C. The story may be the oldest mythological story - but a cohesive document of that narrative is by no means the oldest in the world. The complete written versions of the Iliad and the Odyssey of Homer pre-date the Epich of Gilgamesh by over 200 years. The writing of Homer came into existence some time around 850 BC. There is no doubt that the most ancient, sophisticated, and complete written documents in human history, that make use of an alphabet, are the earliest manuscripts of the Hebrew Bible itself.

In the twenty-fourth day of the month of December; 

In the year five-thousand one-hundred and ninety-nine from the creation of the world, when in the beginning God created the heavens and the earth; 

In the year two-thousand nine-hundred and fifty-seven from the flood; 

In the year two-thousand and fifty-one from the birth of Abraham; 

In the year one-thousand five-hundred and ten from the going forth of the people of Israel out of Egypt under Moses; 

In the year one-thousand and thirty-two from the anointing of David as king; 

In the sixty-fifth week according to the prophecy of Daniel; 

In the one-hundred and ninety-fourth Olympiad; 

In the year seven-hundred and fifty-two from the foundation of the city of Rome; 

In the forty-second year of the reign of the Emperor Octavian Augustus; 

In the sixth age of the world, while the whole earth was at peace— JESUS CHRIST eternal God and the Son of the eternal Father, willing to consecrate the world by His gracious coming, having been conceived of the Holy Ghost, and the nine months of His conception being now accomplished, (all kneel) was born in Bethlehem of Judah of the Virgin Mary, made man. The birthday of our Lord Jesus Christ, according to the flesh.