This is a fascinating verse because of the relationship that it shows between belief and understanding. Usually we approach things the other way around. We want to understand things fully, weigh the pros and cons, and eventually decide whether to commit ourselves or not... preferably even then with an escape clause. And that's a good choice for most things in our world, but spiritual knowledge requires a different kind of confidence. It isn't something that we can learn on our own. We need God's help. It's not because we're dumb or that God can't trust us with the truth. It's that, in a spiritual way, we're still little kids, and it's like we're learning to cross the street and tie our shoes all over again. We have to learn to use new senses and detect new dangers, and our spiritual armor is a little trickier than physical sneakers. God wants to tell us the reasons for all of it, but we have to have a foundation before understanding the grad school lecture on nuclear physics. This is one of the very first lessons, and a great version of it is also in Alma 32, starting in verse 28. To paraphrase, it says that if we compare the gospel to a seed, that we can know whether it is a true or good seed by how it affects us... enlarging our understandings, if we plant it and don't cast it out through unbelief. Ether 12:6 also advises us that we "receive no witness until after the trial of [our] faith."
This seems unfair sometimes. Sometimes we want to wait until we know for certain before taking any action. We want to test every piece of purported truth, look at it with a magnifying glass, and only accept the parts that pass our tests. As I said, with most things in this world, that's a good option. But let's think about some things that are exceptions already. People, for one. If we required background checks and perfection from our family and friends and double-checked everything they said against other sources, we might make ourselves a little safer from error, but very few relationships would survive the scrutiny. Trust and vulnerability are part of almost all kinds of love... to love people, we have to leave ourselves open to possible pain. Trust is also required in school and at work. In order to function, we have to trust the information that people are giving us, at least to some extent, in order to learn new skills and explore new ideas. We don't have the time to become experts in every field and cross-check everything that we come across, so we learn more about who to trust and when to check through trial and error mostly. Come to think of it, the only time we check absolutely everything is when we're scared. Scared of making a commitment, scared of taking a huge step. Scared that someone will take advantage of us. And that makes sense too. Life is scary. Even God can be scary, with all of the hellfire and damnation stuff and the fact that he is God, after all... all powerful, all-knowing. But as with so many scary things, they become less scary when we get to know them. And that's the key... the key to this verse, but also the key to everything... we have to take that leap of faith. We have to believe and hope and trust just enough to try it. To plant the seed in our hearts. To get on our knees and sincerely talk to God and start getting to know him. And once we know he's there, we have to trust him enough to take the next step rather than doubting all over again and going back to square one. To progress, we have to keep trusting enough to keep walking forward.
This doesn't mean, of course, that we don't have questions, or that we should never think or ponder or look things up. We should. It only means that if we let doubts and fears stop us, we stop progressing, and often, like Peter, we start to sink. God gives us the reasons and the explanations along the way, when we have a foundation.... but we have to take that first step, and keep taking steps because we have learned to trust God, not because we know everything and have cross-checked his inexhaustible knowledge. Otherwise, we'll never even learn the first lessons about spirituality... we'll be stuck in unbelief.