Albert Barnes Commentary Acts 19:28

"And when they heard this they were filled with wrath, and cried out, saying, Great is Diana of the Ephesus." — Acts 19:28 (ASV)

Were full of wrath. They were greatly enraged—probably at the prospect of losing their gains.

Great is Diana, etc. The term great was often applied by the Greeks to Diana. Thus, in Xenophon (Ephes. i.) he says, "I adjure you by your own goddess, the great (thn megalhn) Diana of the Ephesians." The design of this clamor was undoubtedly to produce a persecution against Paul, and thus to secure a continuation of their employment.

Often, when people have no arguments, they raise a clamor; when their livelihoods are in danger of being ruined, they are filled with rage. We may learn, also, that when people's financial interests are affected, they often show great zeal for religion, and expect by clamor on behalf of some doctrine, to maintain their own interest, and to secure their own gains.