Everything in God's universe has a purpose. A purposeless idea of the one all-wise Mind would be an impossibility. The carnal or mortal mind presents a counterfeit of God's creation in which many useless things appear to exist and to prosper. But an understanding of the oneness and allness of Mind and the falsity of mortal mind enables us to realize that useless and destructive things are but beliefs which we can overcome by applying the truth.
Christ Jesus saw a fig tree, and the Bible says: "He came to it, and found nothing thereon, but leaves only, and said unto it, Let no fruit grow on thee henceforward for ever. And presently the fig tree withered away." Matt. 21:19 It is evident that this fig tree, being barren, represented an error rather than a truth. Its growth could not have been Mind-directed, else Jesus' pronouncement upon it would not have caused it to be destroyed.
Christian Science teaches that nothing is real unless it is created by God, Mind. But all that Mind has created or creates is harmonious and perfect. What Jesus did was not a destructive act. He unveiled the truth that Life is manifested only in that which is constructive, and the error of a nonconstructive, unfruitful tree destroyed itself.