YOU SAID:

he was certainly the son of evil

INTO JAPANESE

彼は確かに悪の子であった

BACK INTO ENGLISH

he was certainly a child of evil

INTO JAPANESE

彼は確かに邪悪な子供であった

BACK INTO ENGLISH

he was certainly an evil child

INTO JAPANESE

彼は確かに邪悪な子供だった

BACK INTO ENGLISH

he was certainly an evil child