Germany's Catholic Church lost 216,078 members and Protestant churches lost some 220,000 in 2018, according to data published by the German Bishops' Conference and the Evangelical Church in Germany.
Fr. Hans Langendörfer, secretary of the German Bishops' Conference, said in a statement that the Church needs to be "more self-critical and constructive."
"The current statistics are worrying," he said.
"There is nothing to gloss over about the numbers, they confirm a trend that has shaped the Church in recent years."
Church membership in Germany has been declining for years.
The number of people wanting to become priests is also in decline.
In 2005, 122 priests were ordained in the country and just ten years later, only 58 men were ordained priests.
Some 53 per cent of the country's population remains either Catholic or Protestant, according to German broadcaster Deutsche Welle.
While both churches have more than 20 million members, the University of Freiburg has predicted that membership in both churches will be cut in half by 2060.
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