From the right, conservatives are criticizing the contraception mandate that is part of Obamacare. From the left, liberals are objecting to statutes such as the Texas law that prohibits medical personnel from withdrawing "life-sustaining treatment" from pregnant patients -- regardless of the wishes of the patients and their families.

Both illustrate the importance of the separation of church and state, a topic which often revolves around the public placement of the 10 Commandments -- or, as is now the case, the addition of a statue of Satan near the 10 Commandments at the Oklahoma State Capitol.

Historically, both liberals and conservatives have blended religion and politics, usually with disastrous results. We would do well to look to the past as we sort out the church-state issues we face today.

2014 contains the 100th anniversary of the start of the First World War, a conflict which began with the full support of many Protestant theologians. One of the few who objected was Karl Barth, a Swiss theologian who spoke against mixing church and state -- a warning that still rings true.

Initially, Barth saw the church aligning itself too closely with the state. He was a student of the leading liberal European scholars of his day, men who had an optimistic faith in the fatherhood of God and the brotherhood of man. But while serving as a pastor in Switzerland, he saw that Germany was becoming increasingly militarized and that his former teachers were publicly supporting the war policy of Kaiser Wilhelm II. To his horror, Barth realized that God had become domesticated by these theologians and aligned with human institutions.

Today, we run the same risk by allowing religious symbols to become attached to civic structures. A monument of the 10 Commandments outside the Oklahoma Capitol might seem innocuous or even beneficial, but not if it seduces legislators into believing that God is standing by to endorse their actions. We are no less susceptible to believing that God is on our side than were the liberal theologians of Germany.

Singing "God Bless America" is fine. Assuming that God blesses everything American is not.

Barth also saw the danger of the state to the church, after he moved to Germany and Adolf Hitler rose to power. The Nazis began to use the German Church to legitimate their racism and idolatry, and 15,000 pastors aligned themselves with Hitler. Barth joined a group called the Confessing Church that took a stand against the Nazis, and he helped write a statement, the Barmen Declaration, which proclaimed that the church would not allow Hitler to take the place of Christ.

Barth was fired from his teaching position when he refused to pledge allegiance to Hitler, and he returned to Switzerland. But some of his colleagues, such as Dietrich Bonhoeffer, lost their lives for their beliefs.

The separation of church and state reduces such dangers in the United States. Although many people assume that the First Amendment to the Constitution is designed to protect the state from the church, its greater benefit is that it protects the church from the state. Without the guarantee that "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof," ambitious secular leaders could follow the lead of Hitler in exerting influence over the church.

The Obama administration has made an attempt to preserve religious freedom by exempting churches and other religious groups from the Affordable Care Act's contraception mandate. The administration has even created an alternative for quasi-religious institutions. Although the issue is now in court and the final form of the mandate is unclear, efforts to protect religious freedom are worthy of support.

Separation of church and state means that Texas should allow women and their families to make their own faith-based decisions about end-of-life treatment. The current law requiring life support for all pregnant women, which is grounded in a mixture of legal and religious assertions about fetal life, has resulted in a dead woman named Marlise Munoz being kept alive, against her advanced directive and the wishes of her family.

And the statue of Satan next to the 10 Commandments in Oklahoma? Neither should be allowed in a public place, although both are appropriate for display in places of worship. Separation is good for the church and good for the state -- as Karl Barth and others have discovered over the tumultuous history of the last century.