Should We Legislate Morality?

The "Theology of the City" series has been raising a number of interesting questions. One that was posed to me yesterday is: should we or should we not legislate morality?I made the point in yesterday's sermon that the church in America has essentially tried to "re-create Jerusalem." The church has attempted to Christianize the culture, neglecting the obvious fact that it's impossible to do so because true Christianity requires a changed heart, not just an externally imposed moral standard. This led one Coram Deo dude to remark that Christians should stop trying to legislate morality (i.e. working against evil in society using political/social means) because it simply can't work. The gospel works from the inside out, not the outside in.On the other hand, many would say that it IS good and right and godly to influence cultural standards of right and wrong, and political means are a good and legitimate tool God has given for this purpose. This point of view seems to be well-supported in church history... many notable Christians have seen it as part of their duty to work against the structural evil embedded in society by working to change laws and policies that promote sin.What do you think? It seems to me that the convictions on this issue tend to swing back and forth with the political winds. In the 80's and early 90's, at the height of the "Christian conservative" political movement, legislating morality was seen as a good thing. Now that the cool, hip Christians are into new monastic communities and renewable energy and voting for Obama, legislating morality is seen as a bad thing.What are your thoughts? Is there a place for legislation that rewards righteousness and hinders unbiblical living? Or should we seek only to change people's hearts through the gospel, and expect that individual change to have a permeating effect on cities and societies?