From Paul’s previous letter, the Corinthians evidently concluded that he was asking them to avoid all sexually immoral people (as well as all the greedy, swindlers, and idolaters).
Of course (as Paul points out himself), such a command would be impossible to observe. This is not at all what he meant. The church lives in the world and cannot (in fact, should not) avoid contact with people of the world.
10 non pas d'une manière absolue avec les débauchés de ce monde, ou avec les cupides et les ravisseurs, ou avec les idolâtres; autrement, il vous faudrait sortir du monde.