[From the outset, it's worth stating that I'm an atheist (in the soft sense), an agnostic (in a firmer sense), but probably best-described as a Humanist]
Humanists, skeptics, and atheists like to pride themselves on being rational and evidence-based. However, the Sunday Assembly (which I have been helping to organise a bit in Leeds) seems to have brought out the worst kind of ignorant twaddle that I have heard from the community in some time. Most of this seems to centre on “you’re doing something that looks a bit like what people do in church, and that makes it bad”. No attempt at understanding why churches do those things, nor why churches have (until recently) been very successful. With that in mind, here is some science behind the Sunday Assembly:
“Belonging to and participating within a community brings benefits for the participants“
Religious people have places of worship where they meet together in a shared pursuit, build community, and support one another. This kind of social interaction is hugely important for humans, both as a part of our natural, psychological health, and as a social safety net for when things go wrong. There is plenty of evidence for the former from an extensive meta-analysis showing that people with stronger social relationships have a lower mortality rate. In fact, it is possible that the social networks are responsible for all benefits of religion.
“Group singing has beneficial effects in terms of mood and physiology”
Among the more controversial aspects of the Sunday Assembly is the combination of happiness and clapping. Apparently gleefully and rhythmically striking two appendages together is a sign of complete rejection of rationality, and anyone who does this must be religious. What you need to realise is that the group singing at the Sunday Assembly has much more in common with drunken karaoke than the repetitive dirges that plague churches. Imagine singing in the shower, and then imagine there are 200 people also singing as though they are in the shower (but with more clothes – it’s not that kind of organisation). Furthermore, there is mounting evidence for a positive physiological effect of group singing. I admit that that extensive review is based on lots of small-scale studies rather than any large, comprehensive studies, but it does show fairly convincing evidence for a range of benefits.
“Religious people give to charity (both time and money) more than non-religious people”
This is one that atheists really don’t like. We’re simply not as giving as religious people. One of the reasons for this is probably that we aren’t compelled to give 10% of our money to a religious institution, but even when this is taken into account the religious still give more (even to secular charities!). I would suggest that raising awareness of “helping often” (one of the three principles of the Sunday Assembly) will encourage people to give more (not necessarily to the Sunday Assembly!). Sometimes the idea of community giving is something that is contagious, particularly when a group is united for a common fundraising goal.
All in all, I think the Sunday Assembly is a good thing. It’s not for everyone, and if it isn’t for you then so be it – it’s already making a lot of people happy, and I can only see the numbers increasing.