The ever popular dispute of keeping church and state separate has been an issue for years. People simply feel that mixing politics with religion is a serious conflict of interest. However wrong many people see this, the two are rarely separated.
As a matter of fact, there is the long standing tradition of Pope's and U.S. Presidents meeting to discuss important world issues. The ritual started in 1919 with President Woodrow Wilson and Pope Benedict XV. This practice speaks volumes for this hot box issue.
Also, there have been many Christian ministers which have entered the world of politics.
Above is a brief list of pastors and preachers who have "crossed over" into the fascinating world of Government.