I am a civil libertarian, I fear big government that spies on its citizens, I despise taxes that are squandered on pork barrel projects, I loathe deficit-spending, and I could never support the theocratic direction of the current leadership. I believe in agency and allow all religious (and areligious) people to believe what they want to believe. The problem is that a small but powerful group of conservative religious ideologues have tried to hijack the political process and legislate their religion for other people to live. That goes against my concept of agency, and DEFINITELY goes against the libertarian-leaning Republican Party of my youth.
My father often said that big government controls people's lives and we should always be wary of government having too much power. In 1991, he also made two prescient observations. (At the time, we were both Republicans, although I switched parties shortly thereafter.) He said that he was concerned about the religious elements of the Republican Party that appeared to be gaining too much power in the party and he feared that they would eventually take over and push their agenda on others. The other thing he said was that he feared that we would someday be willing as a people to give up many of our freedoms to a government that promised to "keep us safe."
Oh, and I might remind you that those same religious elements are the same religious elements that are on North Temple street with the big signs and loud voices during General Conference.
Also, check out Bryan's origional post, an excellent read if you are LDS, or if you are still trying to figure out how a Latter-Day Saint can be a Democrat.
And, to be fair, you can read the opposition here and here.