From the context of Acts 19:23-29 we can be fairly certain that this riot took place in the spring cir. 55 CE, because the Feast of Artemis (Diana) was about the time of spring equinox. Note, as well, that Luke shows that Paul’s intention to leave Ephesus (Acts 19:21-22) was to fulfill the work of God and not because of a public demonstration against his work done in Ephesus over the past two years and several months (cp. Acts 19:10).
Luke tells us that a certain man named Demetrius had organized a riot against Paul and the work he had done in the Province of Asia. We are also told that Demetrius was a silversmith and a temple maker, but I wonder if his description is not a “form of a technical term used of the trustees of the sanctuary” i.e. the Temple of Diana (or Artemis). An inscription has been found dating to the end of the 1st century at Ephesus concerning a Demetrius who was a temple-warden (neopoios; cp. Luke’s naous poion). Could Demetrius, in fact, be a warden of the temple of Diana and, rather than being a silversmith, had great influence among them or employed a number of them, just as many of the chief priests at Jerusalem either employed or had great influence among all those who profited from the Temple there—whether from herds supplying the sacrifices, money-changers or decorating its edifice? The words “brought no small gain to the craftsmen” refers to Demetrius. That is, he is the one bringing the craftsmen their wealth.
My point is this: Demetrius was concerned over the apparent decrease in temple-worship. The silversmiths may not necessarily have noted a great change in their profits over the past two-plus years, because their business was empire-wide and not just local. Any great change would be first felt by the Temple of Diana, itself. This fits Luke’s context of the rapid growth of the Kingdom of God at Ephesus. It seems the Jews wished to disassociate Judaism from that which was preached by Paul, so Alexander stood up to make his defense of Judaism (Acts 19:33). When the crowed discovered he was a Jew, they went into a two-hour-frenzy, shouting “great is Artemis (Diana) of the Ephesians”. Why would they do this?
I believe the answer is two-fold. First, there was no actual discernment within the gentile community, whether its leaders or the populace, that there was any difference between traditional Judaism and Messianic Judaism (later known as Christianity). Secondly, we are able to discern from the phrase “the Way” in Acts 19:9 and 19:23 that Luke uses it to identify “a socially cohesive movement arising out of and grounded in (the disciples’) shared faith in Jesus.”
Luke uses this terminology in connection with the Jerusalem church (Acts 9:2; 22:4), and its reference of like terminology in Acts 16:17; 18:25, 26; and in Acts 19:9 and 23 in particular expresses an emphasis of the Kingdom of God in a westward movement. Since, as I said above, this Messianic movement would not have been perceived by gentiles as anything other than Jewish, Demetrius is seen as complaining that culture of Diana was being invaded by the culture of the Jews. Paul taught in Athens, and by extension in Ephesus (Acts 19:26), that gods made with hands were no gods at all (Acts 17:24-25, 29). Demetrius noted, first, that the trade of the silver guild would come into disrepute; secondly that the temple at Ephesus would be disgraced; and finally that power or glory of Artemis (Diana), herself, would be brought to ruin (Acts 19:27). In other words the Kingdom of God was indeed invading the world of men, bringing into captivity those who were once held captive by this world’s religious culture (Luke 4:18; cp. Ephesians 4:8 and Revelation 13:10). The invading disciples’ swords were pounded into plowshares for planting the seeds of the Gospel, and their spears were pounded into pruning hooks to permit the greatest and most fruitful growth for the harvest (Isaiah 2:1-4).
 See Robert H. Smith; Concordia Commentary: Acts; page 291.
 I’ve reversed the order of the Luke’s Greek to show the similarity. In the text it is poion naous.
 See Cassidy, Society and Politics, quoted in The Acts of the Apostles, page 584 (Ben Witherington).