And then I started imagining that one day, we could have a rationalist ceremony like this; with all the emotions, but without the bullshit. I viewed the ongoing ceremony as a prototype of something better.

If you haven't, check out Anathem, by Neil Stephenson. It features a monastic order based on mathematics and science rather than any deity. (The book has all the up- and downsides of any other Stephenson novel, which might be a good or a bad thing for you.) It also features a couple of ceremonies.

There is a certain power in ceremonies and most humans react well to that power. Marriages are a good way to channel positive emotions, funerals help people cope with the loss of loved ones, baptisms are about welcoming new humans into a community... Despite the religious connotations those things tend to have, having a rationalist counterpart might indeed be valuable.