Praying or singing in churches isn't actually a mile away from shouting and singing on the terraces of a football match. It's a way of reinforcing group identity and social bonds.
Until now it has to be admitted that humanists haven't been great at creating that sense of community, and that's not surprising: humanists are usually from what you might call The Groucho Marx Tendency, and wouldn't want to join any club that would admit them as a member. The phrase 'herding cats' is overused these days, but it's true that getting humanists to agree on anything is a good deal harder than you might imagine.
But leaving that to one side, one way of getting people, humanist or not, to do something together is to get them to speak a blessing. It's something I often recommend to couples as a way of finishing the ceremony, and I think it's great.
Up to that point, the couple hasn't really seen the guests, so they've got no idea how the ceremony is going down. I have of course because I've been talking to them, so I can see the shining eyes, and the tissue action, and I think it's lovely for the couple to get a sense of the impact on their guests of the words they've chosen to say.
So I generally get everyone to stand, and then repeat the lines phrase by phrase after me, just like learning a foreign language. One of my favourite blessings is an old Irish one, that goes like this.
Rich in blessings,
Slow to make enemies,
And quick to make friends.
But rich or poor,
Quick or slow,
May you know nothing but happiness
From this day forward.