Only a few neo-Confederates and Covenanters may disagree, but most Reformed Protestants assume that men ordained to the ministry of the word may not serve in capacities that involve the use of the physical sword (police, military, and even civil magistrate). The logic goes something like this:
Civil magistrates may not assume to themselves the administration of the Word and sacraments; or the power of the keys of the kingdom of heaven; or, in the least, interfere in matters of faith. (Confession of Faith, 23.3)
One could well suppose that if magistrates (who hold the civil sword) can’t have the keys of the kingdom, those who do have the power of the keys shall not assume the power of the civil magistrate. That fits with what the Form of Government says about ecclesiastical power:
All church power is wholly moral or spiritual. No church officers or judicatories possess any civil jurisdiction; they may not inflict any civil penalties nor may they seek the aid of the civil power in the exercise of their jurisdiction further than may be necessary for civil protection and security.(3.4)
So imagine what happens to this delicate balance between civil and ecclesiastical power when all of a sudden every Christian is a minister. How could we ever allow a minister to fight in a war, to operate under the authority of the Department of Defense, to bring criminals to justice?
If Christians may not serve as soldiers or as executioners, then we need to revise assertions like this:
Public life is not just about politics but all the areas of human activity — thefamily, the workplace, shops and restaurants, leisure and the arts. It is the specific role of lay people to sanctify each and every environment of the world.
Sometimes “every” and “all” make you wish for dualism.