Do you only believe in what you can see, touch, feel, etc?
No, actually - this is a common question, and typically a result of poor communication. The characterization is that the atheist will look around the room, not see a god visually, and then conclude there can't be a god, because he/she didn't see one. We're not that obtuse.
The misconception likely arises because we might say, "We do not see any evidence for...". What is meant by "see" is not sight, but rather general observation, even if that observation is implemented through a scientific instrument. Atheists aren't perfect communicators, as it turns out.
Skeptical atheists tend to be evidence driven, not sensory driven. Even if it's indirect evidence, we'll work with that.
- We can't see or feel magnetic fields, but we accept they exist, because we can analyze its affect on metal objects.
- We can't directly see or feel atomic nuclei, however, we can detect them using various gold-foil experiments.
- We can't see any evidence for the big bang, yet we can collect evidence, such as the Doppler effect on light and microwave background radiation, either of which we can't detect with the naked eye.
One can devise tests to demonstrate to a life-long deaf person that sounds exist. One can demonstrate to a life-long blind person that sight exists. One can demonstrate to a life-long (completely) color-blind person that color exists. Even if these people can't directly perceive a phenomenon, you can indirectly demonstrate that it exists as well as associated mechanics and behaviors.
We're perfectly fine with indirect or circumstantial evidence. What you're asserting simply has to manifest, in some detectable way, in this reality.
So, instead of stating the above explanations every time the topic comes up, we tend to just say "see".
Frequently, people claim to have psychic powers, or the ability to detect water with a stick (dowsing), or a whole range of other assertions. If we can establish a scientifically valid and executed test for these claims, and they pass, that gains credibility with atheists.