Losing faith in Santa

Atheists routinely compare faith in God to childish faith in Santa Claus. According to one study I read about, conducted by two Cornell professors, children generally outgrow belief in Santa Claus around the age of 7-8. 

It's striking that kids that young already have the cognitive development to become skeptical of Santa Claus. This is something they generally figure out on their own.

Let's compare that to another claim. Atheists, as well as "progressive Christians," think Bible writers espouse a three-story universe. So, for instance, Bible writers allegedly thought the dead descended to the Netherworld. 

The origin for that belief supposedly goes back to burial customs. If the dead are buried, then it's natural to associate the place of the dead with the underworld. It must be underground. 

There are, however, obvious problems with that inference. To begin with, it's not as if the average grave had backdoor or trapdoor that tunneled down to the Netherworld. You dig a shallow grave for the corpse, and that's that. And, of course, the skeleton remained. 

Another problem is traditions of the dead going up rather than down. The soul ascending to heaven. 

But here's the larger issue. On the one hand, many children around the age of 7-8 lose faith in Santa Claus. They begin to ask common sense questions about the feasibility of that scenario. They do this without any prompting from adults.  

On the other hand, atheists assure us that adults in the ANE were incapable of posing logistical questions about the feasibility of a three-story universe.