Question: The oldest item in the Diocesan Museum depicts the battle of a the god of what ?

Context paragraphs:
Diocesan Museum (Cortona): The Diocesan Museum in Cortona is an art museum in Cortona, Tuscany, Italy.  Located on the former site of the local Church of Gesù, it houses works of art by artists such as Fra Angelico, Pietro Lorenzetti, Bartolomeo della Gatta, Luca Signorelli and Sassetta.  The oldest item in the museum is a marble Roman sarcophagus (2nd century AD), depicting depicts the battle of Dionysus.

Museo Diocesano: The Diocesan Museum of Milan ("Museo Diocesano di Milano" in Italian) is an art museum in Milan housing a permanent collection of sacred artworks, especially from Milan and Lombardy.

Diocesan Museum (Genoa): The Diocesan museum of Genoa is located in Genova in the region of Liguria.  It is found inside the old residence of the canons of the Cathedral of San Lorenzo and is accessible through the cloister of San Lorenzo.  The cloister, built in the 12th century, is characterized by two levels of arches resting on double Romanesque columns with leaved capitals.  In the 17th century two sides of the building were modified, with the double columns substituted with heavy pilasters in order to support the above two floors constructed for additional space.  The museum houses objects from the diocese of Genoa and the surrounding area, including sculptures, paintings, frescoes, illuminated manuscripts, and a series of liturgical items, as well as an archeological area.

Diocesan museum of sacred art (Arezzo): The Diocesan museum of sacred art in Arezzo (also known as MuDAS) was founded in 1963 but opened regularly to the public only in 1985, and was housed in several rooms above the sacristy of the Cathedral of San Donato.  In 2011 it was relocated to the first floor of the bishop's residence.  The museum exhibits works of art and liturgical items, from the 12th to the 19th centuries, that come from the cathedral and other churches in the diocesan territory, significant for their religious and cultural significance to Arezzo and the surrounding area.  Highlights of the museum include several works of Giorgio Vasari and the "Pace di Siena".

Hildesheim Cathedral Museum: The Hildesheim Cathedral Museum (German: Dommuseum Hildesheim) is the Schatzkammer (treasury) and diocesan museum of Hildesheim, which illustrates over a thousand years of art and church history in Lower Saxony.  It is located in historic rooms off the southern transept of the Hildesheim Cathedral.  During the cathedral renovations of 2010, the nearby church of St Antonius and part of the cathedral cloisters were converted into display rooms for the museum.

Kolumba: The Kolumba (previously Diözesanmuseum, "Diocesan Museum") is an art museum in Cologne, Germany.  It is located on the site of the former St. Columba church, and run by the Archdiocese of Cologne.  It is one of the oldest museums in the city, alongside the Wallraf-Richartz Museum.

Diocesan museum of Ascoli Piceno, Italy: The Diocesan Museum in the Italian town of Ascoli Piceno is located in one wing of the ecclesiastical palazzo, which also contains the city's pinacoteca and the state archeological museum.

Assisi Diocesan Museum: The Assisi Diocesan Museum, in the city of Assisi, was founded in 1941 by bishop Giuseppe Placido Niccolini to preserve the most important works of art of the Assisi Cathedral and of several oratories of Assisi's confraternities.  The museum is located underneath the piazza of the cathedral and has a collection consisting of about 300 works of which 100 are on display, exhibited in the museum's nine sections.

Dionysus: Dionysus ( ; Greek: Διόνυσος "Dionysos") is the god of the grape harvest, winemaking and wine, of ritual madness, fertility, theatre and religious ecstasy in ancient Greek religion and myth.  Wine played an important role in Greek culture, and the cult of Dionysus was the main religious focus for its unrestrained consumption.  His worship became firmly established in the seventh century BC.  He may have been worshipped as early as c. 1500–1100 BC by Mycenean Greeks; traces of Dionysian-type cult have also been found in ancient Minoan Crete.  His origins are uncertain, and his cults took many forms; some are described by ancient sources as Thracian, others as Greek.  In some cults, he arrives from the east, as an Asiatic foreigner; in others, from Ethiopia in the South.  He is a god of epiphany, "the god that comes", and his "foreignness" as an arriving outsider-god may be inherent and essential to his cults.  He is a major, popular figure of Greek mythology and religion, becoming increasingly important over time, and included in some lists of the twelve Olympians, as the last of their number, and the only god born from a mortal mother.  His festivals were the driving force behind the development of Greek theatre.

Diocesan Museum in Pelplin: The Diocesan Museum in Pelplin (Polish: "Muzeum Diecezjalne w Pelplinie" ) holds one of the finest collections of medieval art in Poland.  It is located in the town of Pelplin in Tczew County (Pomeranian Voivodeship) and is managed by the bishopric of the Roman Catholic Diocese of Pelplin.  It bears the name of Bishop Stanisław Wojciech Okoniewski (1870–1944), the founder of the museum "()", who died in Lisbon during World War II.  Founded in the Second Polish Republic in 1928 during the interwar period, the collections have been housed in a modern-style building complex since 1988.

Supporting paragraphs: Diocesan Museum (Cortona) Dionysus
Answer: grape harvest, winemaking and wine, of ritual madness, fertility, theatre and religious ecstasy