Unfortunately, this doctrine of continuing revelation can sometimes be a stumbling block for our testimonies.
Why a stumbling block?
Let's have a little history lesson.
Prior to 1978, the priesthood was restricted to men not of African descent. I won't go into specifics, because they aren't relevant to this post - but just know it was a complicated and strange policy, and many people didn't understand it. Even today, the best explanation we have (officially) is this statement from the Church:
“The origins of priesthood availability are not entirely clear. Some explanations with respect to this matter were made in the absence of direct revelation and references to these explanations are sometimes cited in publications. These previous personal statements do not represent Church doctrine.”In 1978, the Church issued an official declaration, based on revelation, extending the priesthood to all worthy male members of the Church.
Recently I have been hearing members of the Church say that they hope that the Church will eventually embrace same-sex marriage because, after all, the Church was "wrong" once (referring to the priesthood ban). They seem to be viewing the 1978 revelation as a sort of apologetic "Whoops, we were wrong, we're sorry" admission.
Honestly, it's hard not to see it that way, especially given all the personal statements and opinions that were offered as explanations for the priesthood ban, most of which were abhorrent, even in the early and mid 1900s when they were originally offered.
If so many apostles, prophets, and other Church leaders could be so misguided and racist, then might not our Church leaders today be bigots and homophobs? It isn't a completely illogical leap.
Except for one small principle which might help us sort out this whole issue.
At General Conference in April 2012, Elder Christofferson taught:
…it should be remembered that not every statement made by a Church leader, past or present, necessarily constitutes doctrine. It is commonly understood in the Church that a statement made by one leader on a single occasion often represents a personal, though well-considered, opinion, not meant to be official or binding for the whole Church.While any number of racist sounding explanations for the priesthood ban can be readily produced by any proficient Googler, I think you would be hard pressed to find any of these comments listed in proclamation format, signed by all fifteen living apostles at the time of the statement's utterance, and good luck finding teachings by every single apostle since quoting the statements. In fact, most of the apostles either said nothing about the subject of the ban, and few quoted the misguided (in my opinion) statements of their brethren. We must always remember that prophets are still just men. Moses, arguably one of the greatest prophets, was scolded by God Himself. Even Joseph Smith had issues, admitting his youthful indiscretions and at times failing to be content with God's answers to his prayers and requests.
On the other hand, The Family: A Proclamation to the World is a document affirming the sanctity of marriage between a man and a woman, and testifying that gender is an eternal characteristic. This document was signed by every one of the fifteen apostles of Jesus Christ living when it was written, and it has been quoted by every newly called apostle since. I think it is safe to consider the document, and its call to "responsible citizens and officers of government everywhere to promote those measures designed to maintain and strengthen the family as the fundamental unit of society" as being "official [and] binding for the whole Church".
It can definitely be hard to recognize what is revelation and what isn't, what is scripture, and what are the philosophies of man. Again, we can go back to our fundamental belief in revelation - not just continuing revelation through prophets and apostles, but personal revelation. Each and every one of us is entitled to receive our own revelation - as Levar Burton says "But you don't have to take my word for it."
More reading about revelation:
Becoming a False Prophet to Ourselves