Yep, he had this idea. That doesn't make it a right idea.

We didn't talk about right or wrong but silly.

Let's compare it to the alternative the morality is partially biologically hardwired and partially culturally determined.

Let's do what partially biologically hardwired and partially culturally determined is not exactly the battle cry under which you can unite people and get them to adopt a new moral framework. It also has the problem of not telling people who want to know what they should do what they should do.

Do you, by any chance, believe there is a causal connection between these two observations that you jammed into a single sentence?

Yes, I do think that Marxism and Socialism has a lot to do with spreading atheism in Europe. Socialist governments did make a greater effort to push back religion and make people atheists than democratic governments did.

If I hear Dawkins talk how it's important that atheists self identify as being atheists to show the rest of America that one can be an atheist and still a morally good person, than that does indicate to me a problem of American culture that's largely solved in Europe. Socialist activism has a lot to do with why that's the case.