[quote=@Primal Conundrum]
If our power grows enough, would we be able to forge a new afterlife destination for our followers?
[/quote]

You actually have a few options with this. You could create your own by yourself. You could find an existing realm and take it as your own. There are existing realms that are empty or abandoned that you could take or, if you're feeling ambitious, you could steal one. Finally, there are legends that you can get designer realms made by certain deities.

In short, yes.

[quote=@Primal Conundrum]
It feels to me like being benevolent would likely be the safer and more rewarding long-term strategy, while taking sacrifices and being a bit more bloodthirsty would be a high-risk high-reward path that may have a weaker future ahead of it. Easier to grow the numbers of the faithful when you aren't killing them / forcing them to kill, after all.
[/quote]

Basically this. There are ways to make sacrifice more worthwhile, but they're not realistic at this moment. Also they come with lots of bad juju. 

[quote=@Primal Conundrum]
Also, correct me if I'm wrong, but the way you were describing the world it sounds like it's a modern day parallel?
[/quote]

I apologize for not mentioning that earlier, but yes. It's basically today's world.