One of the more challenging sayings of Jesus relates to prayers that a mountain be cast into the sea. The expression of a mountain being cast into the sea is sometimes presented by teachers as though God were saying that if someone prayed in faith, God would toss any old mountain into the sea, much like a child might through a stone in the lake, just for the fun of it.
However, in both the Old and New Testaments, casting a mountain into the sea is a fear-inducing calamity and sign of judgment, much like an earthquake.
Psalm 46:2 Therefore will not we fear, though the earth be removed, and though the mountains be carried into the midst of the sea;
Revelation 8:8 And the second angel sounded, and as it were a great mountain burning with fire was cast into the sea: and the third part of the sea became blood;
The passages (there are two synoptic accounts of this saying of Jesus) in which we find Jesus mentioning the prayer about the mountain are sometimes interpreted, as I noted above, as simply a trivial exercise of God's power. Other times, ministers attempt to spiritualize this by suggesting that the mountain of our sins will be removed if we pray to God for that (appealing perhaps to Micah 7:19 He will turn again, he will have compassion upon us; he will subdue our iniquities; and thou wilt cast all their sins into the depths of the sea.). While such is a true doctrine, I do not believe it is the true sense of this passage.
In the context of the passages, Jesus has been interacting with the scribes and chief priests (Matthew 21:11-15; Mark 11:9-18). They are critical of him because he is receiving the praise of children, who call him the Son of David and the Prophet of Nazareth. It seems that Jesus and his disciples are visiting the temple on essentially a daily basis, returning at night to Bethany.
In both passages we are told as well about a fig tree. From the passages we learn that Jesus came on the way from Bethany to Jerusalem and found a fig tree that had leaves but no fruit, and he cursed it. On the following day, returning along the same path, the disciples noted that the cursed tree had completely withered, and they marveled.
It is upon this occasion, the marveling at the withering of the fig tree, that Jesus made his saying:
Matthew 21:21 Jesus answered and said unto them, Verily I say unto you, If ye have faith, and doubt not, ye shall not only do this which is done to the fig tree, but also if ye shall say unto this mountain, Be thou removed, and be thou cast into the sea; it shall be done.
Mark 11:23 For verily I say unto you, That whosoever shall say unto this mountain, Be thou removed, and be thou cast into the sea; and shall not doubt in his heart, but shall believe that those things which he saith shall come to pass; he shall have whatsoever he saith.
Notice a word that is frequently overlooked. Jesus does not say simply, "say unto a mountain," but "say unto this mountain." What mountain is he speaking of? There is the possibility that it is any mountain between Bethany and Jerusalem, but in the context of both accounts, the very next thing that Jesus does is to enter into Jerusalem and specifically the temple (Matthew 21:23; Mark 11:27).
Thus, it is reasonable to view Jesus' remarks as being directed toward the mountain to which they were approaching, namely Jerusalem, and especially the temple mountain. With this in mind, what Jesus is speaking of is of the destruction of Jerusalem. The destruction of Jerusalem, and especially the temple mount was complete. As prophesied in Matthew 24:2, even so it was carried out:
And Jesus went out, and departed from the temple: and his disciples came to him for to shew him the buildings of the temple. And Jesus said unto them, See ye not all these things? verily I say unto you, There shall not be left here one stone upon another, that shall not be thrown down.
And as he went out of the temple, one of his disciples saith unto him, Master, see what manner of stones and what buildings are here! And Jesus answering said unto him, Seest thou these great buildings? there shall not be left one stone upon another, that shall not be thrown down.
That Jesus is speaking of the judgment of Jerusalem in our present passages is also demonstrated from the picture of the fig tree. The fig tree represents, it appears from the context, the hypocritical Jewish leadership. They had a zeal for the law, at least outwardly, and consequently from a distance resembled a fig tree full of leaves. However, upon examination, they are not found to have fruits, and consequently they were judged.
In the case of the fig tree, the the fig tree withered, but in the case of Jerusalem, the whole mountain was destroyed, cast into the sea as it were, by the Romans. Indeed, the Jewish historian Josephus tells us that following the destruction of Jerusalem, "[General Titus] then went down with his army to that Cesarea which lay by the sea-side, and there laid up the rest of his spoils in great quantities, and gave order that the captives should he kept there; for the winter season hindered him then from sailing into Italy." (Josephus, Wars of the Jews, Book VI)
This passage should remind us of the fearful judgment of God on hypocrites. Let us careful examine ourselves lest we be found to be fruitless fig trees ripe for judgment. Do not delay, for while we do not know when the Lord will return, we do know that none of us will live for ever. We will all then appear before the Lord our maker, to be judged. If you, dear reader, are trusting in the rock of mount Jerusalem, or of the seven hills of Rome, or of the Swiss alps, rather than trusting in the Rock alone of which it is written:
Psalm 18:2 The LORD is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower.
Then this day turn in repentance from your sin, place your trust in Christ alone, and humbly beg him that he would bring spiritual fruit into your life through the operation of His Most Holy Spirit, who together with the Father and the Son is God Almighty, to whom be glory and praise both now and until the ages of ages.