a leap of faith

US /ə liːp əv feɪθ/
UK /ə liːp əv feɪθ/
"a leap of faith" picture
1.

an act of believing in or accepting something unseen or unproven, often despite evidence to the contrary

:
Starting a new business requires a leap of faith.
She took a leap of faith and moved to a new country without a job.