My two eurocents ...
I'm Atheist
The wife is generic Christian
We sent both our kids to a catholic primary school. Son never much cared for gods and such. But Daughter did buy into it. And she's always trying to come at me with biblical gotchas ... well until she figured out my reply was always the same "does this seem sensible to you". And usually, she'd figure out on her own that the bible is a pile of otter's nipples. So, along comes 6th grade
[1] and up pops the question of confirmation. Ok, so we tell the daughter, do it or don't do it, you get a party
[2] either way.
And she chooses to sign up, partly because her best friend will as well
[3]. But, nonpurturbed, the daughter goes ahead with the cathechism anyway. And ... a lackluster gotcha or two later, she increasingly focusses on the secular aspect of things ... the arts and crafts, the games, the songs. At the end of cathechism, she's closer to Atheism then ever.
She hasn't abondoned the concept of god entirely, but she'll occasionally start to say something about god and suddenly stop. You can actually see her doing a mental doublecheck and then change to subject. And we're ok with her talking godstuff. It's not like we go "Ain't no god talk in this house!!!"
Inquisitive minds will, when left to their own devices figure it out ... usually.
Incidentally, this 6th december, The Son admitted that he no longer believes in Saint-Nicholas, and that he hasn't for over a year
[4]. Recently, he told me that there's a lot of simularity between god and Saint-Nicholas
[5]. Also, the subject of his confirmation has come up, under the same conditions, do or do not but there will be a party and a new outfit
[6] either way. His reaction ... 'meh, don't wanna'.