The phrase preaching to the choir is explained nicely in Wikitonary:
preach to the choir
(idiomatic) To speak as if to convince a person or group of something they already believe. quotations ▼
Often used to imply that a speaker is addressing the wrong audience or is deliberately addressing a compliant, non-challenging audience.
The first translation on YouDao translates it very literally:
the second translation is completely wrong (你和唱诗班说吧) and the third is quite literal as well:
While, seemingly, correct - the above translations could hardly express the nuances of addressing the wrong audience by trying to convince them of something they already believe in Chinese.
Any ideas for a good colloquial translation of "preaching to the choir"?
ed: 给和尚念经 -or- 念经给和尚听 are quite good alternatives!