"We need to show the people we understand what it's like to be unbelievers."

I came across this sentence in some of my notes which, to me, sums up missional living. I think I must have found it either online or in a book . Sadly I didn't take note of the source. Anyone know where it comes from? Anyone as struck by it as I am?

On the same subject, this definition of a missional church from Acts 29 is helpful.