a/the

Only the first sentence sounds natural. And it would read You are an extraordinary person.

The rest is unnatural and does not sound like a native speaker.

How about, You always do the right thing and never moralise.

The last sentence is way too wordy, cut out the words and you no longer need a/the.

It was always wrong to laugh at him.

Haha, I'm glad for your help. But it's not an essay. I just need to figure out what article we should use with attribute+noun in those situations. I know, it sounds unnatural, but still, what do I have to do?

Those situations would not arise. People would never say "You never say a/the moral thing."

I'm not too sure what is meant by that, I guessed it was about moralising but it was still a guess.

As it's something we would never say and I'm not sure what you even mean by it I can't advise on definitive articles. It's wrong regardless of whether you use a or the.