It is always interesting to see how ancient traditions persist even up to the modern era. Whether it is the resurgence of Eastern meditation practices in modern healthcare or the lingering presence of the Christmas tree in the living room, many customs have been co-opted from their original surroundings into a wholly different setting. Not only is this practice nothing new, it is oftentimes done purposefully. With regards to the Christian appropriation of non-Christian (i.e. pagan) cultural elements, the process is called Interpretation christiana, and a great example of it can be seen in the history of how the Cup of Ptolemies became a Chalice of Christ.
The Christian Chalice
Before it was stolen from the Louvre in 1804, the Cup of Ptolemies had served for hundreds of years as the Eucharistic chalice for the communion wine at the Basilica of St. Denis in northern Paris. The lost artifact was eventually recovered later in the 19th century, but by then it could no longer serve as a chalice. The cup itself is an intricately carved piece of onyx with two handles and measures 3.3 x 4.9 inches (8.4 x 12.5 cm). The cup has a small nub on the bottom, on which it can stand, but was presumably lifted using the handles.
That, at least, is how its pagan creators intended it to be used. Sometime around the Carolinian Renaissance (ushered in by Charlemagne and lasting from the 8th to 9th century), a cone-shaped base was added to the cup to make it a proper chalice. Later, in the 12th century, the famous Abbot Sugar of St. Denis embellished it with gold and precious stones so that the chalice base would be as fantastic as the onyx cup. We know this only from sketches made of the artifact, particularly the engravings made by Michel Félibien in 1706. The chalice’s base was not recovered with the cup (but the thieves were caught in Holland). The French police believe it was broken off and melted down so that the gold and jewels could be better sold. The market for onyx was apparently less accessible.
More at SOURCE