Mark 11:23
Truly I tell you, if anyone says to this mountain, go, throw yourself into the sea, and does not doubt in their heart but believes that what they say will happen, it will be done for them — the mountain-into-the-sea saying uses the local geography of the Mount of Olives standing above the Dead Sea as the extreme example of faith's potential. The saying is not a formula for getting things by saying them but a communication of the scope of what faith-saturated prayer can accomplish. Does not doubt in their heart is the key condition: the doubt that undermines prayer is not intellectual questioning but the heart's fundamental uncertainty about whether God hears and acts.