LeGrand Richards
"I doubt if there was a Christian minister in all the world who would have said there was no devil at the time the Book of Mormon was published in 1830, and yet when a questionnaire was sent out by the Northwestern University School of Religion in 1934 to five hundred Christian ministers, of the five hundred, fifty-four percent, or two hundred and seventy of them, said: ’There is no devil.’ Thirty-nine percent, or one hundred and ninety-five, said there would be no judgment day; and eighty percent were opposed to teaching that hell was a place of burning…If the world could just get rid of the devil, probably it would be a different world. They little realize how much his influence and power is being felt.
“…What in the world could the devil, the enemy of all righteousness, desire more than to make our young people think that chastity is outmoded? To accomplish this, he must make them believe there is no devil, and that there is no hell or judgment day. Thus ’he whispereth in their ears, until he grasps them with his awful chains, from whence there is no deliverance.’” (Conference Report, Oct. 1949, p. 51,53)
Marion G. Romney
“A corollary to the pernicious falsehood that God is dead is the equally pernicious doctrine that there is no devil. Satan himself is the father of both of these lies. To believe them is to surrender to him. Such surrender has always led, is leading now, and will continue to lead men to destruction.” (Conference Report, Apr. 1971, p. 22)
Harold B. Lee
"We see some of the signs…we know lead us downward. Some are called taverns; some are called lounges; and some are called roadhouses. They have bright, neon-lighted signs outside with catch-phrase names. They are dimly lighted inside; they have sensuous music. These are the unmistakable trademarks of the hell holes of Satan.
Nephi spoke of some teachings against which we must be on guard lest we follow that road, when he said that in a day to come, which we realize now is our day, there would be those who would ’teach us to become angry against that which is good, to lull us away into carnal security and to flatter us by telling us there is no devil, there is no hell.’ (See 2 Nephi 28:20-22.) (Conference Report, Apr. 1956, p. 110)