ANSWER; This is an Oriental proverb for the removal of some stupendous obstacle or the conquest of any appalling difficulty. It is to be symbolically interpreted, and not literally, unless the spirit of God should in a supernatural way inspire miracle working faith for such an object, which he has never yet done. When Christianity went forth from Jerusalem to conquer Jewish opposition, and pagan persecution, faith removed the Alpine mountains which stood in the path of a dozen unarmed, and unlearned fishermen and peasants. This text does not encourage anything spectacular or arbitrary. We are dependent upon the Holy Spirit for a knowledge of what we should pray for. When we know this, it is easy to believe. When God wants us to work miracles he will inspire in us miracle working faith.
— Steele's Answers p. 110.