In an IDEAL world ... it would be nice to have the laws of the land line up with our values. However ...
We are not living in an ideal world. Who is to say that those "in power", even if they had perfect laws that pleased us in every way, might not in a year or two decide that perhaps veneration of icons is actually idolatry, and of course if the laws represented our values, idolatry would be illegal.
I hope I'm explaining that well enough.
I do think certain things should be against the law - those things I believe immoral from a Christian standpoint. But ... it can open a door for things being legislated we would not like.
Abortion, same sex marriage? I still think it should be against the law. Abortion because it is killing babies, and same sex marriage because it is essentially the state defining a sacramental union. (And much more in each case.)
There's also the matter that laws don't necessarily govern people's consciences. People will still break laws. Instead of making abortion illegal, such that abortions are still performed, but in ways that have their own problems attached, I would find it much more effective and satisfying to see people value human life at all ages and stages, and make protection of and caring for that life a priority. If people did that, then even if the laws allowed all sorts of injury to human life, the hearts of people would keep them from doing such things, and the hearts of others would keep them from feeling they needed to.
But we don't live in an ideal world. Not by a long shot. And each of the things I've mentioned has a host of connected issues that I'm not sure people even see until after we begin "going down that road". Sometimes I'm disheartened to see that, if there is a bad fork to take on ANY road, society itself seems to take it, making the consequence of each decision even worse than we realize.