Every temple lessens the power of Satan on the earth

“Every foundation stone that is laid for a Temple, and every Temple completed according to the order the Lord has revealed for his holy Priesthood, lessens the power of Satan on the earth, and increases the power of God and Godliness, moves the heavens in mighty power in our behalf, invokes and calls down upon us the blessings of the Eternal Gods, and those who reside in their presence.”

- Pres. George Q. Cannon, “The Logan Temple,” Millennial Star, Nov. 12, 1877, 743. As quoted by Pres. James E. Faust, Second Counselor in the First Presidency, "Perseverance," Ensign, May 2005, p. 53
http://www.lds.org/ensign/2005/05/perseverance?lang=eng#footnote8-25905_000_021

God has reserved spirits for this dispensation

“God has reserved spirits for this dispensation who have the courage and determination to face the world, and all the powers of the evil one, visible and invisible, to proclaim the gospel and maintain the truth and establish and build up the Zion of our God fearless of all consequences. He has sent these spirits in this generation to lay the foundation of Zion never more to be overthrown, and to raise up a seed that will be righteous, and that will honor God, and honor Him supremely, and be obedient to Him under all circumstances.”

- Pres. George Q. Cannon, First Counselor in the First Presidency, as quoted by Elder David A. Bednar Of the Quorum of the Twelve Apostles, "Things as They Really Are," Ensign Jun 2010, p. 23