Why was the temple endowment such a strength to the pioneers as they left Nauvoo and traveled to Salt Lake City?
The blessings made available to the children of men in God’s holy temples are the greatest blessings that are given by God to men on the earth. The path to the glory of exaltation in the celestial kingdom of God is through the doors of the temple; it can be achieved in no other way. The Lord has said,
Therefore, verily I say unto you, that your anointings, and your washings, and your baptisms for the dead, and your solemn assemblies . . . are ordained by the ordinance of my holy house, which my people are always commanded to build unto my holy name (D&C 124:39).
Great strength comes to those who are endowed in the holy temples. As an example, there is a vast difference in commitment between a person who chooses not to use tobacco because he realizes that it is bad for his health and a person who does not use tobacco because he has made a sacred covenant with the Lord to obey the Word of Wisdom. The choice of the first person comes from a certain rationale and judgment on his part, and he has no more obligation to follow his course than his own wisdom dictates.
But to the second person, who has made a covenant of obedience with the Lord, his abstinence from the use of tobacco has become a matter of principle, and matters of principle are not open to negotiation. Thus he who obeys a certain concept as a matter of principle has much more strength to stay his course than does a person whose judgment is a matter of convenience or rationalization.
The pioneers were following the Prophet as a matter of principle; and far from being a matter of convenience, to the contrary, their decision to leave all their possessions and endure all the hardships and even death on their march to the West represented a great sacrifice. It was specifically their commitment to principle that gave them the strength to endure all that they had to endure to obey those who spoke for the Lord, and establish the Zion of the West in fulfillment of prophecy.