believe in
US /bɪˈliːv ɪn/
UK /bɪˈliːv ɪn/

1.
wierzyć w
to have faith in the existence of something or someone
:
•
Do you believe in ghosts?
Czy wierzysz w duchy?
•
I believe in God.
Wierzę w Boga.
2.
wierzyć w, ufać
to have confidence in the ability or goodness of someone or something
:
•
I believe in you, you can do it!
Wierzę w ciebie, dasz radę!
•
She still believes in the power of kindness.
Nadal wierzy w siłę życzliwości.