In 391 AD, Theophilus, the patriarch of Alexandria, was encouraged to oppress paganism in Alexandria by edicts declared from the Roman Empire calling for the strict enforcement of Christianity as an official religion of the empire. He first took the cult objects from a pagan temple in order to parade them on the street in an insulting manner. This resulted in a riot that caused Christians to lose their lives. Four months after publicizing his first edict, the Roman emperor Theodosius I felt obliged to repeat his prohibition against pagan worship, this time addressing it to the military governor and prefect in Egypt.
The pagans of Alexandria resolved to take refuge in the Serapeum and fortify it against attack; captured Christians were forced by the pagans to sacrifice there and were tortured if they refused to do so. Theodosius I stated that the slain Christians were to be considered martyrs, but he also wanted to pardon the pagans who barricaded themselves in the Serapeum. The emperor’s main objective was to completely destroy the Serapeum, since he believed that it was a source of evil; “as the imperial rescript was read aloud and it became clear that the pagans were being held responsible, the Christians, shouting their joy, assailed the temple.”11
The Christians, however, were hesitant about damaging the statue of Serapis since they believe that doing so would bring about a major disaster. After Theophilus ordered a soldier to chop of the head of the statue with an axe, nothing disastrous happened. The Christians proceeded in dismembering the statue; while the head was carried around the city, the rest of the statue was set on fire. While busts of Serapis were being destroyed throughout Alexandria, they were widely replaced with crosses found on doorposts, entrances, columns, windows, walls, and even incised in stone in the destroyed temple of Serapis. Theophilus later had other temples in Alexandria demolished in the same manner as the Serapeum was destroyed, and the images of the pagan gods were melted down to be used as pots and other utensils in a new kind of religious building: the church.
While the destruction of the Roman Serapeum of Alexandria is highly documented, the destruction of the Ptolemaic one is not. Archaeologists and scholars believe that the latter Serapeum was destroyed by Jews, rather than Christians. Since they were the ones who invented the god Serapis, the Ptolemies had a much stronger connection to the deity. The Romans, on the other hand, only adopted Serapis and the Serapeum later in Antiquity and thus had a weaker connection to both, despite the fact that their Serapeum was similar to that of the Ptolemaic Serapeum. While both the Ptolemies and the Roman emperors had their own eventual downfalls, the Ptolemies were faithful to their religious identity as pagans until the end; the Romans chose to abandon paganism for Christianity once the latter gained more followers throughout the Ancient world. Therefore, the Ptolemaic Serapeum can be considered to be of greater significance than the Roman Serapeum in terms of the adherance to paganism on the part of the Ptolemaic kings.
11. Encylopaedia Romana- The Destruction of the Temple of Serapis http://penelope.uchicago.edu/~grout/encyclopaedia_romana/greece/paganism/serapeum.html