For if there be no Christ there be no God; and if there be no God we are not, for there could have been no creation. But there is a God, and he is Christ, and he cometh in the fulness of his own time. (2 Nephi 11:7)
The first part of that verse is fascinating reasoning that sounds very logical, and yet it leaves out many assumptions, trusting the reader to figure them out. It is instructive to think about what assumptions make it so Nephi can state this with such confidence.
“if there be no Christ there be no God” – A Messiah to suffer for all is absolutely important to the definition of God. A Christ provides for mercy, and a God must show both justice and mercy to be God.
That being said, we live in a world where it might seem difficult to see the justice of God. That’s because God is long-suffering and offering mercy, holding back the day of judgment so we have time to lay hold on that mercy.
“if there be no God we are not, for there could have been no creation” – God must create because it is part of His perfections. And He must create men and women to become more like Him because that is the perfection of creation. And of course, that means He must provide means whereby He can have mercy on them, so that presupposes a Christ to suffer for their sins.
Unbelief might cause people to fall through the cracks of Nephi’s logic, but for those who don’t, we can see our very existence as evidence of God and of Christ.
Someone else has pointed out that life balances as it were on the head of a pin of perfect optimums, which if disturbed, disrupt whole systems and make life untenable on biological, chemical, and astronomical levels. From that perspective, perhaps commandments are ways of asking us to spiritually climb onto more pins and balance, so that we can discover new optimums of spiritual creation that we never knew existed. Naturally, there will be lots of wobbly pins and lots of falling off, but the atonement makes it so that our falls don’t nail us to the ground when we land on our faces.