Have you observed the wind? We can not see but we can see what the wind can do right?
We can not see God for example but we can see his creation. That includes us and the awesome way we are made. So yes there are things that exist that we simply can not see with our eyes but we know they are there
Despite not seeing them, most people believe such things as wind, electricity, gravity, anger, and a host of other very *real* things do exist. The fact is, we see evidence of them, of their effects, and of their nature.