Sustain Doesn’t Mean Agree With
Often in the church, a certain segment of members will accuse others of not sustaining church leaders because of a political, policy, or interpretive disagreement. I’ve heard stories of people having their temple recommends revoked because of a stated intention to vote or lobby for various civil laws. This overreach often comes about because of a prevailing belief in the church that sustaining one’s leaders means agreeing with one’s leaders. However, that isn’t what sustain means.
We can disagree with someone, even vigorously so, while still sustaining them. We need look no further than the example of Russell M. Nelson to demonstrate this. During the time that Gordon B. Hinckley and Thomas S. Monson were president of the church, the church ran the “I’m a Mormon” ad campaign and sponsored the movie “Meet the Mormons”. And now that Nelson is president of the church, he took to the pulpit and denounced the use of the term “Mormon” to refer to members of the church and called the term a victory for Satan. Clearly, he did not agree with his predecessors. Not only did he disagree, but he disagreed very strongly, to the point that he thought they were playing into Satan’s hand. Yet, presumably as an apostle, he held a temple recommend and had to affirm that he sustained Hinckley and Monson.
So, if sustain doesn’t mean agree with, what does it mean? When searching the scriptures, most of the references to sustaining deal not with humans’ attitude toward their leaders, but rather with God’s attitude toward us.  God doesn’t always agree with us. When we hurt others, God wants us to stop and to change. But God stays by our side and helps us on the road to continual improvement.
- “Cast thy burden upon the Lord, and He shall sustain thee.” 
- “Yea, forty years didst thou sustain them in the wilderness, so that they lacked nothing; their clothes waxed not old, and their feet swelled not.” 
- “I laid me down and slept; I awaked; for the Lord sustained me.” 
Even in the context where the sustaining is being done by a person, not by God, the act of sustaining is not an act of intellectual or theological assent. It’s an act of nourishing and feeding. Isaac sustained his son Jacob with wine and corn.  In the only scriptural example of someone sustaining the prophet, the unnamed widow of Zarephath sustained Elijah by giving him a cake and some oil. 
So, the way we sustain the leaders of the church is the way God sustains us. We lighten their burdens, nourish them, and assist them in meeting their righteous goals while fervently hoping and pleading for them to change the things that cause harm. Just as God can do that for us while disagreeing with some things that we do, so we can do that for church leaders even while disagreeing with some things they do.
And maybe one day the winds will change and the things we disagree with will change, too.
——- The word “sustain” is used 13 times in the standard works. Eight of those are in the Old Testament, three in the Doctrine and Covenants, and two in the Pearl of Great Price. Of those references, two are about our obligations toward civil law, one is a procedural matter regarding canonization of Official Declaration 2, one refers to church members “sustaining damages” from their persecutors, and the rest refer to a person being given aid.  Psalm 55:22  Nehemiah 9:21  Psalm 3:5  see Genesis 27:37  see 1 Kings 17:9-16