Mark Hendrickson in an essay called "The Liberal Temptation":
Christians who happen to be political liberals are fond of citing scriptural verses exhorting believers to perform charitable deeds. Indeed, there are many such verses, and they mean what they say. But what the liberals invariably fail to see is that the Bible never indicates that it is the Christian's duty to compel others to do charitable works; rather, Christians themselves are expected to do those works. There is no charity by proxy in the Bible. True charity comes from an inner, spiritual impulsion, not from outward political compulsion. That is the essential difference between Caesar and Christ.
Indeed. Christ commanded the rich young ruler to "sell all that you possess and distribute it to the poor", but he did not break into the man's house and rob him, as government does. In fact, at no point in the Gospels did Christ urge the use of government force to compel people to adopt his teachings.
This is why Hendrickson has incorrectly referred to Bible-based policy making as "the liberal temptation". It is a statist temptation, found readily among conservatives. James Dobson and Pat Robertson are conservatives who, just like their liberal counterparts, try to force their vision of Christian ethics on people by using government power.
Compulsion is the enemy of evangelism, for there is no true conversion or sanctification unless is is uncoerced. Forced virtue, Left or Right, is no virtue at all.
UPDATE: Oops! I forgot to hat tip Joe Carter for this article.