You know, these questions simply don't arise in most families. None of the grans I know would dream of getting involved in religion of any kind, and especially not involving the grandchildren. It isn't that they are atheists - I would call them non-theists: they don't give any of it a thought.
One gran, a close friend, was a catholic most of her life, even serving on the Parish Council, but about 15 years the church started going backwards, slowly easing away from the reforms of Vatican 2. At the same time she quietly stopped going to mass every week, then hardly ever went, then stopped, having removed herself from any church positions.
I think this sort of thing is happening all over, and the tighter the church squeezes out reform, the more parishioners slip away, and the less reason they find to come back.
Once gone, reason prevails, suspension of disbelief becomes less and less possible, and that's an end to it.