Tercüme - İngilizce-Brezilya Portekizcesi - The heart that prays to God is afraid of nothing

"ko-u" is a verb that means literally to "ask (someone) (for something)," to "request (something) (from someone)."
It is not often used colloquially and so has a bit of a literary quality. I therefore translated it here according to the context as "prays." The context leaves it open just what this heart asks God for, i.e. probably strength or courage or such like...

Or: Não tem medo de nada.