When an amazed Peter noted to Jesus that the fig tree had withered, Jesus’ response was simply that they should “have faith in God” (Mark 11.22). This was a gentle rebuke for the disciples’ lack of faith in the power of His word. Such faith believes in God’s revealed truth, His power, and seeks to do His will (see 1 John 5.14; Matt. 21.21).
The expression Jesus used, “this mountain…into the sea” (v. 23), was related to a common metaphor of that day, “rooter up of mountains,” which was used in Jewish literature of great rabbis and spiritual leaders who could solve difficult problems and seemingly do the impossible. Obviously, Jesus did not literally uproot mountains. In fact, He refused to do such spectacular miracles for the unbelieving Jewish leaders (Matt. 12.38). Jesus’ point is that, if believers sincerely trust in God and truly realize the unlimited power that is available through such faith in Him, they will see His mighty powers at work (see John 14.13, 14).
“Whatever thing you ask when you pray, believe that you receive them, and you will have them” (v. 24). This places no limits on a believer’s prayers, as long as they are according to God’s will and purpose. This therefore means that man’s faith and prayer are not inconsistent with God’s sovereignty. And it is not the believer’s responsibility to figure out how that can be true, but simply to be faithful and obedient to the clear teaching on prayer, as Jesus gives it in this passage. God’s will is being unfolded through all of redemptive history by means of the prayers of His people—as His saving purpose is coming to pass through the faith of those who hear the gospel and repent. See James 5.16.