The Himmler quote brings up mostly religious sites in the first few pages of search results. The assertion that Nazi Germany was an atheist regime is outright false, for which there are multiple lines of evidence, beginning with small things like 'Gott mit uns' belt buckles and ending with guidelines for book burnings
which include both books promoting materialism and evolution and those which criticise Christianity.
The idea that society falls apart without religion is also false, as evidence by the hellholes that are Western Europe, Scandinavia, and most other developed countries other than the US. Indicators of societal health generally negatively correlate with religiosity and faith. Not sure which studies do the best job of showing this, but this
is a start. Which is not a surprise given the amount of time and effort religions tend to put into impeding medical and social progress, such as opposition to the HPV vaccine, safe and legal abortion, sex education, and many more.