My hypothesis

[Mister Agenda]

From Wikipedia:

"Religion is a cultural system of behaviors and practices, world views, sacred texts, holy places, ethics, and societal organization that relate humanity to what an anthropologist has called "an order of existence".

"Religious humanism is an integration of humanist ethical philosophy with religious rituals and beliefs that center on human needs, interests, and abilities."

Religious rituals? Dafuq?

Some people like them. In the US, Ethical Culture is probably the most prominent version, but you could make a case that Unitarian Universalism amounts to religious humanism in many congregations, particularly those founded as Fellowships. As far as the UU goes (much more common, most cities have one), they attend a service on Sunday morning, there's hymns (but they don't mention Jesus), announcements, an offering (and often half of the collections go to a charity like Planned Parenthood, the Progressive Network, an Animal Shelter, a food bank, homeless assistance, etc.), and a service which is basically a talk on some topic or another. There may be a meditation. Older, more traditional Unitarian churches may be as close to Christian as makes little difference, but many in the South and West established after the Fifties don't have actual prayer or worship. The previous pastor of the UU in my city of Columbia SC was Neal Jones...he's an atheist, so the service was definitely religious humanist while he was around. The interim minister is a little harder to pin down, but her services aren't overtly theistic.