It gets worse than you know. Not only is the doctrinal god not real... not even the Stoic thiest god more valid than agnosticism. (Epistemology)
It gets worse: There is nothing that says the words of human are more valid than looking to nature. There is 0 way to factually chose between them. (Epistemology)
It continues to get worse: Circles aren't real, they are a construct of human language. Even our knowledge of material things is subject to the same limitations. Organic molecules see the world, and different organic molecules turn this into logical thought. Then we vibrate some air particles as we explain to others. (Ontology)
Anyway, its much worse than you think. Do not read philosophy if you want to continue being happy like you are. All paths in philosophy lead to nihilism.