Is 모두가 correct usage?

ANSWER: No.

Today I was reading Lee O-deok's (이오덕) book "우리글 바로쓰기" and noticed the following sentence:

"말을 살리는 일이 바로 목숨을 살리는 일임을 모두가 깨달았을 때 비로소 우리는 이 땅에서 당당하게 살아남을 겨레가 될 것이라 생각합니다."

The book is about writing Korean sentences correctly and clearly, but the above sentence is neither correct nor clear. Why? For one thing, 무두 is an adverb, not a pronoun, so he should not have written 모두가, which suggests it is a pronoun. And what does he mean by 모두가? Does he mean "all people," "all Koreans," "all writers"?

If he meant "all people," he should have written either "사람이 모두" or "사람 모두." If he meant "all Koreans," he should have written "우리 나라 사람이 모두," "우리 겨레가 모두," or something similar. If he had meant "all writers," he should have written "작가가 모두," "글 쓰는 사람이 모두," or something similar.

Also, instead of writing 모두가 깨달았을 때 비로소 우리는, he could have just written 우리 모두 깨달았을 때 비로소.

And I would have divided the sentence into two sentences to make its meaning clearer.

Finally, I see no need for 생각합니다 since it is clear that he is giving his opinion.

So here is how I would rewrite the sentence:

"말을 살리는 일이 바로 목숨을 살리는 일입니다. 이 것은 우리가 모두 깨달았을 때 비로소 이 땅에서 당당하게 살아남을 겨레가 될 것입니다."

"Saving language is saving lives. When we all realize this, we will, for the first time, become a people who can live in this land with dignity."

In the book, the author looks at the sentences and writings of others and makes suggestions for improving them, but in the process of doing that he seems to have neglected his own writing. Still, there is a lot of good information and suggestions in the book.

From Dong-A's Prime Korean-English Dictionary