1/5
Lesia, that’s two questions really—(1) elaborate on the theory, and (2) apply to gay marriage.

I’ll tackle the first, and either duck or take a limp stab at the second.

If we assume that the Holy Spirit has been trying to guide our theology from the beginning, but that since we are constantly evolving (intellectually, not biologically), she has in fact adapted her message through time to our capacity to understand, then wisdom dictates that we respect past theological positions because somewhere in there is prior divine inspiration. And further, I would argue, the best way forward (that is the way that is most likely to survive into the future with respect) is to strive to identify that trace of the Spirit to be found in our past rather than just throw it out for something new. That is, we should strive to find the thrust, the trend, the movement, the directionality that we presume the Spirit has left throughout our past. 

This gets really complicated in practice.