Contrary to [TurretinFan's] assertion, the fact that something has become highly politicized is precisely why more caution is called for, not for the amplitude to be turned up. This actually sounds like the sort of reasoning that compelled Protestant liberalism to suggest that the world sets the church’s agenda: the bigger the worldly deal the more the church should get involved.There are two problems with this comment. First, the question is not simply whether the world generally makes a big deal about something. The attention that the world gives to something shows what is on the minds of the people. Sometimes that is a relatively significant issue (like abortion), sometimes it is a relatively insignificant issue (like who happens to be topping this week's Top 40 chart, or which sports team is winning). The world may actually think more about the latter topics than the former, but the church will spend more time on the former than the latter, because of the greater moral concerns.
Second, even if your reaction is "more caution is called for," you are still involved in a situation in which "the world sets the church’s agenda: the bigger the worldly deal the [less] the church should get involved." The fact that you swap "less" for "more" doesn't change the fact that the world is setting the agenda.
The church is in the world but not of the world. Churches in rural Alabama may have a very different "world" to contend with than those in Amsterdam. Nevertheless, they do need both to react and to transform the world in which they find themselves, by preaching the gospel of repentance and faith.
"Zrim" also asks: "since every aspect of life has moral dimension then wouldn’t the church also have to take on everything in terms of its moral primacy?" The fact that everything has a moral dimension does not mean that everything deserves the same amount of attention. Some sins are in themselves and by reason of several aggravations more heinous in the sight of God than others. The slaughter of the unborn falls into that "more heinous" category, and consequently when it is prevalent calls for more vocal opposition.