I used to go to church from the age of about 11 until I was around 16 or 17. We (my siblings and I) decided to get baptised at 11 so as a family, we had to attend church beforehand. The minister was really nice (he taught us RE in school). We continued going after we were baptised. We then had the next ceremony (it wasn't called confirmation but it was the equivalent), I think we had to go to some sort of evening classes beforehand.
There was an area on the foyer where patents could take their young children to play during the service but the service was played via speakers in to there. All children went down to a Sunday school during the first hymn and came back at the end. I can't really remember what we were taught but we were split up by age group. As we got older we started helping out and teaching some of the sessions. I was glad of that as sitting through the whole service was boring.
There were quite a few children at the church, a number around our age. We were all quite good friends. We played in the church band together. We were involved in some of the rotas of the church eg greeting people, handing out hymn books, doing the collection, serving the teas and coffees, which made us feel part of the church.
The whole church had an annual outing and there was also a youth church weekend away with other churches, which was fun.
We attended the church youth group which was run weekly in the church hall and was very cheap. The youth group wasn't religious and most of the kids who attended didn't go to the church.
I did believe in religion at that point but enjoyed the social aspect too. I liked being included in the jobs within the church. We were about to do the alpha course when I decided it was all nonsense and I didn't believe any of it anymore. I think my siblings followed suit shortly afterwards (I can't remember if they did the alpha course). My grandmother stopped going about a year or two later when the nice minister left and was replaced with a very boring minister.
So, lots of waffle, but basically feeling welcomed, included and valued. Having people my own age there helped. And I think there has to be some religious feeling there (or even just questioning whether there might be) - I hate going in to church nowadays, feel deeply uncomfortable (had to go for remembrance service when I volunteered with a uninformed youth organisation) and refuse to join in with prayers becausei dibt believe any of it.