@degenerateafro : Altena fading in and out is because she used up so much of her power before, not because she lose her statue (the statue that Kane picked up was for a nameless goddess that's already dead, the creator God made it link to Altena so that Kane's prayer to the 'mountain goddess' would go to her)
It's BECAUSE she didn't have that much power that the idea of spreading her worship to give her more power was brought up, so that next time she has to use her power for miracle she wouldn't be at risk of disappearing.
And per Altena's explanation (with MAYA's own speculation) here:
https://mangadex.org/chapter/887198/28
https://mangadex.org/chapter/887198/29
https://mangadex.org/chapter/887198/30
https://mangadex.org/chapter/887198/31
1. Noir herself, without all the monsters' prayers after being purified by Kane, was akin to a nameless God (i.e. Altena herself at one point)
2. The monsters' prayers is what threatens to turn her 'back' to being evil god.
3. It's literally Kane's 'wish' that made Noir who she is right now. So in a way he has 'created' the goddess Noir in the same way his prayer has made Altena a goddess.
So as long as they can clearly cutoff the current overlap between Noir and evil god, the statue, and build a new statue to keep praying for her, then she should be able to keep existing even if she's a lot weaker than when she was evil god.