One of the charges often levied against the LDS Church is that the doctrines change over time. For example, from http://20truths.info/mormon/doctrine.html and http://wakeupmormons.blogspot.com/p/latest-changes-to-lds-doctrine.html:
Changing Doctrine Over Time
In one of his more regrettable statements, Hugh Nibley said that one of the hallmarks of Mormon truth is that it has never changed over time:
"The gospel as the Mormons know it sprang full grown from the words of Joseph Smith. It has never been worked over or touched up in any way, and is free of revisions and alterations. Joseph Smith took the same elements that have proven so recalcitrant and so hopelessly conflicting in the hands of the churchmen and threw them together, with an awful lot of other stuff, to follow Brodie, into a single wildly chaotic mess. And lo and behold, everything fell into line of its own accord; all the haphazard elements in the bewildering heap fitted together perfectly to form a doctrine so commanding that not even a hint of rhetorical paradox is needed to support it, and no 'Gregorian compromise' with a pleasure-loving world has been necessary to assure its vigorous growth." (Hugh Nibley, No Ma'am, That's Not History)
The facts, however, show otherwise.
The site then goes on to list several doctrines that have, clearly, changed over time.
Other arguments levied by more "mainstream" Christians against the LDS Church include references to Malachi 3:6, which starts out "For I am the LORD, I change not;" The claim is that the LDS teachings are in contradiction with this.
They say, "If God never changes, then Truth never changes." They cite changing doctrine as evidence that the Truth taught in the LDS Church changes, and therefore, can't really be from God.
So, from an LDS perspective, what is the defense to this charge and these changes?