IPA: //ʌn.bɪˈliː.vɪŋ//
KK: /ʌnˈbɪlivɪŋ/
Not accepting something as true or real; having doubts about something.
She gave him an unbelieving look when he told her the news.
Unbelieving → It is formed from "un-" (meaning not) and "believe" (from Old English "beliefan", meaning to have faith or trust). The word "unbelieving" means not having faith or trust in something.
Think of 'not' ('un-') having 'faith' ('believe') — that's why unbelieving means not having faith.