make a leap of faith

To take action based largely or entirely on one's faith that it is correct or will work, despite having little or no evidence or assurance thereof. Our family has maintained control of this company for over 100 years, so we're really making a leap of faith in letting an outsider to run the organization. We kind of made a leap of faith when we decided to move some place where we didn't know anyone, but it was definitely the right decision.