Do Christians have faith in oxygen/air?

[SteveII]

Okay, so now I'd distanced myself from the church for a few months now.

Three months ago, my partner asked me if I had faith in the air we breath.

Of course my answer was no, because it is obviously and irrefutably there.

You could guess what that person asked next! 

Next question was: "So why do you have faith in God?"

Thinking about that question for several weeks now, and I'm having a strange feeling. 

Am I overthinking because I can't think of a strong answer? What am I missing?

I think it is a bad comparison. Faith in an inanimate object does not carry any meaning past depending on an object's physical properties. Faith in a person carries way more meaning because as a person, they can let you down, there are motives, abilities, promises, circumstances, and interaction that are all reasons/components of "trust and confidence". In addition, this is all contained in first definition below--not even touching the second definition. 

faith
fāTH/
noun

1. complete trust or confidence in someone or something.
   "this restores one's faith in politicians"
   synonyms:
   trust, belief, confidence, conviction; More
   
   
2. strong belief in God or in the doctrines of a religion, based on spiritual apprehension rather than proof.