take a leap of faith

1. To do something based largely or entirely on one's faith that it is correct or will work, despite having little or no evidence or assurance thereof. I know that a lot of marriages don't work out, but if you really love this guy and want to spend your life with him, then you need to take a leap of faith. I feel a bit wary that people seem so eager to take a leap of faith about driverless cars being free to drive in our streets.

2. In a video game, to make one's character jump when the player is unable to see where they will land. Because the game doesn't offer any control over the camera, there are a number of occasions where you have to take a leap of faith and just hope for the best.