Naturally the Lord cannot reveal the mysteries of his kingdom to the scoffer, neither can he to the member of the Church who is not faithful. If a man does not exercise faith why should he have the revelations concerning the kingdom of God revealed to him? They cannot understand them because they are ‘fallen’ man, and without the enlightening influence of the Holy Spirit, they are as the Lord expressed it, ‘carnal, sensual and devilish.’ [ Mosiah 16:3.]
It is written that when the disciples asked the Savior why he spoke in parables, he answered: ‘Because it is given unto you to know the mysteries of the kingdom of heaven, but to them it is not given. For whosoever hath, to him shall be given, and he shall have more abundance: but whosoever hath not, from him shall be taken away even that he hath.’ [ Matthew 13:11–12.] The Lord further said, ‘Give not that which is holy unto dogs, neither cast ye your pearls before swine, lest they trample them under their feet, and turn again and rend you.’ [ Matthew 7:6.] There were occasions when he instructed his disciples not to reveal certain manifestations until after his resurrection.
Of course, a man who believes that man has descended from lower forms of life, and by gradual development after an enormous length of time evolved from fish to reptile and then to ape, can never understand the fall of man and the atonement. These truths are mysteries to him and only contempt and abuse do they receive from him.
(Joseph Fielding Smith, Man, His Origin and Destiny, pp. 358–60)