Understanding of "take a leap of faith"

Question

I met the following sentence:

Sometimes you have to take a leap of faith.

What does it mean exactly? Does it mean you have to trust people or believe something is true?

Answer 1

The concept is a play on words.

"Look before you leap." is an ancient saying in English, and exists as a sentence far before English became a language. It is basically as statement that before you do something you can't change after it is started (the leap) you should consider where you will land (the look).

"A leap of faith." uses the word "faith" which is belief without knowledge. It replaces the "Look" in the other phrase, so now instead of considering where you will land, you trust without knowledge that you will land in a better place. So, you are committing to a course of action (the leap) hoping that you will land in a better place without knowledge that it will be better.

Why do both these phrases use "leap?" Probably because once you leap (your feet leave the ground), there's little you can do to alter where you land.

Answer 2

"take a leap of faith" means an act of believing in or attempting something whose existence or outcome cannot be proved or known. Or to another way to put it, a belief or trust in something intangible or incapable of being proved.

Example:

It required a leap of faith to pursue this unusual step of transplanting an animals' heart into a human patient. Source

The leap of faith here represents how humanity has probably never tried this before and has not been proved to work, but decided to go ahead and believe it will work.

In your example,

Sometimes you have to take a leap of faith.

It reveals how sometimes you believe in something or yourself that something will work, but is not "proved" and unknown.