That is something that could change from time to time, society to society and even person to person..
Is the idea of God and after-life....knowledge or ignorance? I would say definitely knowledge....and you would say definitely ignorance!
Knowledge is not just information. Its about how we put together information meaningfully. The same information can be put together knowledgeably or ignorantly....to give different pictures of reality.
Interesting use of the word 'knowledge'.
From a philosophical point of view, defining exactly what one means by (propositional) knowledge is a bit tricky. Traditionally (Plato IIRC) it was viewed as "justified true belief"
*, that is, it's something you believe, it is true and you can offer justification for it (the idea being that you can't have knowledge from a random guess, even if it's true). However, there are some rather tricky counterexamples (Gettier) that seem to show that there are significant problems with this definition.
Science, on the other hand, deals with theories can be justified from the current, intersubjectively verifiable evidence (Popper). There is no requirement that theories be true in some absolute sense, just that they have stood up to all attempts at falsification.
To take your examples. The word 'god' is way too imprecise (it is understood to mean so many different things to different people) for the statement "god exists" to even form a meaningful proposition, without further definition.
However, I have yet to hear anything approaching a reasonable justification for any of its many definitions (except those that equate 'god' to the universe, some part of the universe, or the laws of nature). So the traditional notion of knowledge is out (unless you can provide a definition and justification). As for intersubjectively verifiable evidence goes: I have never heard of any.
The afterlife would also fall down in both cases.
So, how would you define knowledge in such a way as those two beliefs are included and different, far-fetched ideas (that you don't like) are excluded (purple aliens from Andromeda, a different and incompatible god to the one you defined, the ghost of Plato talks to you in your dreams every night, the moon is a hologram, alien abductions, and so on)?
* The Oxford Dictionaries site still give this as the phiosphical sense of the word.
http://www.oxforddictionaries.com/definition/english/knowledge