That is the kind of power Christ gives us -

Sometimes I wonder about such power if it's being used correctly, and how would one go about doing so?

These people were devout (see: Teenager from faith-healing family dies in Oregon), and believed everything the scripture told them.

Did they just not believe enough? They were not bad people. And the excuse "God works in mysterious ways" is very unsatisfying when their own keep dying.

What are they doing wrong? And why didn't Jesus respond to them? They were obviously depending on his words to be true.