There was previously SE site for Atheism, which unfortunatelly was closed very quickly. Is it possible to fill this proposal, once it reaches the beta, with the questions and answers from previous site?
I hope you're working on a new scope or a new approach to this site, and not just rehashing the same community that only recently failed to build a dynamic, lively site.
Most of the core users lost interest and left the site. The users I talked to found that the content had become uninspired and "painfully uninteresting" — that's their words; not mine — so why would you want to dig up that warmed-over content in your brand new site?
In a more general sense, I'm not a big fan of any kind of migrations to fill a new site. It's a failed initiative that has been tried and failed.
I prefer to see early community ask their own questions and build their own inventory of expertise and users. Moving questions often means the post looks somewhat out of context on the new site. Many of the questions will find themselves "ownerless" as users will not likely have accounts on the new site. The tags wont match, and the quality may not be all that good — It all begins to look a bit like a dumping ground.
I wouldn't support this migration of content. It's a bad idea all around.