The clerk asked this question to assure the crowd they were right and to comfort them. AT: "every man knows that the city of the Ephesians is temple keeper ... heaven." (See: [[rc://en/ta/man/translate/figs-rquestion]])
# who does not know
The town clerk uses "not" to emphasize that all of the people knew this. (See: [[rc://en/ta/man/translate/figs-litotes]])
# temple keeper
The Ephesian people maintained and guarded the temple of Artemis.
# the image which fell down from heaven
Within the temple of Artemis was an image of the goddess. It had been fashioned from a meteorite which fell from the sky. People thought that his rock had come directly from Zeus, the ruler of the Greek gods (idols).
# Seeing then that these things are undeniable
"Since you know these things"
# do nothing rash
"do not do anything before you have had time to think about it"