What if a Non Muslim or could be a Muslim commies a sin like zina out of ignorance ?

[truthseeker63]

If a person commits zina – for example – and does not know that zina is haraam, he will not be punished and is excused for his ignorance. But if a person knows that zina is haraam but he does not know that the one who commits zina deserves the hadd punishment, then he has no excuse and the hadd punishment must be carried out on him, if the conditions for that are met.

http://islamqa.info/en/ref/20237

What if a Non Muslim or could be a Muslim commies a sin like zina and did not know it was haram ? What happens to people who comit sins out of ignorance
? Should they get the hadd punishment ?​