One of the benefits of being so evidence-based is that it is relatively easy for me to realign my beliefs when presented with new and better evidence (the 'better' qualification is a crucial element). If you provide me with better evidence, I'll respond with better beliefs.
It was the process of gaining more evidence that led me to abandon my belief in a worldwide flood. There were just too many holes in the story. Too many reasons it couldn't be true and not enough reasons it could. I found that as I asked questions about the flood--how could there be enough water to 'baptize the earth?'; wouldn't the elevation change cause asphyxiation?--the apologists' answers became more and more implausible.
Evolution was another issue that gradually grew on me. First, I was a pure creationist, then I bought into the six creative periods. Next it was some conglomeration of creationism and evolution (probably not unlike Intelligent Design) and finally settled on evolution. At this point, I'm a fairly strict evolutionist.
The implications of these modified beliefs are, I imagine, exactly like what strict biblical interpretationists feared about evolution. Evolution has crushed my confidence in certain beliefs that are widely accepted as simple fact in orthodox Christianity and/or Mormonism.
Let me list a few.
First, I don't believe Adam and Eve actually existed. At least not as we envision them in our canon. I don't believe in the first-humans-ever-and-distinct-parents-of-the-human-race mythology. Rather, I suspect the man we know as Adam was the first man God chose to be a prophet. And he was likely chosen at a time when God observed the evolution of a species capable of the moral reasoning on which agency is based.
Things snowball from there. Reject the Adam-as-first-man philosophy brings into question numerous other beliefs. And so I find it unlikely that Eve was formed from a rib; or that the Garden of Eden was on the American continent (or that it even existed, for that matter).
It seems so much more plausible to me that Adam and Eve were the first leaders chosen to establish gospel teaching. That they did so at the very earliest stages of Humanity's development, and that the Flood was a literary device to bridge the gap between oral and written history. It seems more plausible that Moses (and the actual biblical authors) used the common creation myths of the day to convey eternal principles.
This has added a subtle new dimension to how I think about some things. Not too long ago, I came across an online discussion about Eve's motivations for taking the fruit of the Tree of Knowledge. I can't really comment on Eve's motivations because I don't believe there was an actual Tree or actual Fruit. I think the more relevant question is, what were the motivations of the person who wrote the allegory in designating Eve as the first to partake? (And that is a separate entry entirely).
I suspect that I will get a certain amount of pushback about rejecting the Adam and Eve story. The Creation, the Fall, and the Atonement are crucial aspects of the Mormon narrative. I suppose the argument goes that if there is no Adam and Eve, the there is no Fall. And if there is no Fall, there is no Atonement. But I don't think that's true. If the Creation story of Genesis is an allegory--a teaching device--and we acknowledge a loss of information between oral and written histories, then it seems perfectly plausible to conclude that the Fall--being the representation of when Man became accountable for their sins--happened in some other and probably boring way (the same boring way children become accountable?)
It's also possible I'm completely wrong about all of this. Which is fine. I don't particularly care if Adam and Eve were a real thing or not (so why write all this, you ask? I was bored and cranky).
So let me wrap up with those things I do believe. I believe that God recognized that we wouldn't be able to live up to His strict and perfect expectations. I believe that God had the wisdom to comprehend the competing needs of justice and mercy. And I believe, in His eternal pragmatism, He provided a Savior that could balance those competing needs. Most importantly, I believe that even with zero understanding of how God established His presence among humanity, those things I do believe are far more valuable than those things I don't.