1
general::
Phrase(s): *a leap of faith
Fig. acceptance of an idea or conclusion largely on faith. (*Typically: be ~; make ~; require ~.) • We had to make quite a leap of faith to accept his promise after the last time he let us down.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
A belief or trust in something intangible or incapable of being proved. For example, It required a leap of faith to pursue this unusual step of transplanting an animal's heart into a human patient.
American Heritage Idioms