8 For it seemed good to the Holy Spirit, and to us, to lay upon you no greater burden than these necessary things: 29 that you abstain from things offered to idols, from blood, from things strangled, and from sexual immorality.[g] If you keep yourselves from these, you will do well.
Isn't that a bit odd? The Bible is saying that sexual immorality is on a level with eating blood sausage, Polish duck blood soup or eating a steak from a cow that may have been strangled in the slaughterhouse?
The laws against sexual immorality are restated by Moses in Leviticus and the fact these laws applied before Moses and applied to all nations is also stated by scripture as follows
Lev 18:24 Do not defile yourselves with any of these things; for by all these the nations are defiled, which I am casting out before you.
God did cast out nations for sexual immorality but never for eating shellfish.