Separation of Church and state is a heresy.
The two can be distinguished, but never separated.
Man is made in the image and likeness of God. For this reason, man will always try to replicate his relationship to God in his dealings with other men. Thus, no man can actually succeed in separating his theology from his politics. It isn't possible.
In a democracy, where politicians are selected and elected, politics is necessarily a reflection of the theology that dominates the electorate. When a Protestant Congress outlawed contraceptives, that political body was merely reflecting 2000 years of Christian tradition. From the 1930s onward, when judges began to overturn the Comstock laws, we saw the United States move away from its Christian roots towards a eugenically-minded agnosticism.
Today, with Hillary Clinton and Donald Trump as the representatives of our major political parties, we see an inchoate paganism. It is not the paganism of the Norse, the ancient Greeks or the ancient Romans, all societies which celebrated martial values and delighted in constant war. Rather, it is a paganism that denigrates warfare but delights in sensuality.
Our desires have become our god, and now that god drives our politics.
Our theology will always be reflected in our politics - it cannot be avoided.
With this election, many of us are shocked to discover that Obama is correct - we are no longer a Christian nation.