Confessing Church (Bekennende Kirche) was the name for a group of churches in Germany before and during World War II. When many churches supported Nazi policies on many things in 1933, a variety of churches chose not to, and were forced to go "underground" to meet. A group of these, mostly Lutheran, Reformed, and Union pastors and congregations, issued what was called the Barmen Declaration in 1934, re-affirming the focus of the church on Christ rather than Nazism.
Many of the leaders of the Confessing Church, such as Martin Niemoller and Dietrich Bonhoeffer, spent time in concentration camps. Christians who did not agree with the Nazis thus were without leadership, and were forced to worship much as they did in the early days of the Roman Empire. The Confessing Church engaged in various forms of resistance, notably hiding Jews from the Nazi regime.