Jesus and Politics

In the season leading up to the 2012 elections, one of my seminary professors, who was also a pastor, shared a letter he had written in response to a congregant who had been urging him to address particular social issues. In this letter, my professor explained that he did not believe Christians were called to involve themselves in politics.

In response, I took pieces from this letter and incorporated them into the following fictional letter from an Anglican minister to the famous abolitionist, Thomas Clarkson. (The underlined portions of the fictional letter are the pieces I copied verbatim from my professor's letter.)
Dear Thomas Clarkson, 
Thank you so very much for taking the time to send me these materials concerning the slave trade, but I must confess that I just do not have a burning desire to get involved with the political process.
You ask me to preach against slavery from the pulpit, circulate your petition after services, and urge my congregation to boycott sugar. However, as a representative of the Christian community, I have no intention to influence the broader culture with Christian morality. It is not our calling, as a Christian community, to legislate morality for unbelievers. If we are determined to change the culture by legislating biblical morality, where do we draw the line? If we are to outlaw slavery, must we also outlaw cursing and drunkenness? 
And just whose “Christian” morality do we legislate? For many years, only the eccentric Quakers opposed slavery. You are the first Anglican minister to publicly stand against the trade, and there are still very many in our community who find nothing wrong with slavery. 
A Christianity that expends its energies trying to fix the world by legislating morality alienates unbelievers, because all they hear about is what we are against, rather than what we are for. As I am sure you have noticed, many people do not like William Wilberforce. He makes them angry, and has brought ridicule on the entire evangelical community. They speak of the “damnable doctrines of William Wilberforce and his hypocritical allies,” and many consider him a traitor to the Crown. 
Finally, I am not convinced that we could change the broader culture, even if we wanted to. For millennia, all cultures and all religions have accepted the institution of slavery, and the economy of the empire is dependent upon the trade. Furthermore, even assuming that we could change the values of the dominant culture, to do so by wielding political power would be to engage in an ill-fated agenda that has, again and again, throughout church history, compromised the very message of the cross that we preach. 
Instead of petitioning parliament and boycotting sugar, why don’t you spend your time helping the poor and telling people about Jesus? 
As I hope this letter demonstrates, the arguments offered against political action simply do not work. The command to love our neighbors compels us to strive for justice in society. Therefore, I do believe Christians should involve themselves in politics. Here is one political issue which particularly deserves our attention: