I've done enough LSD to know that there's a force that is greater than what we experience on our normal physical plane of existence.
Now that's funny. Do you believe it is reasonable for a person to make such a claim as an entirely unknown aspect of reality based upon their chemically distorted sensations? I would suggest not. You may say it inspired in you a curiosity, but that remains merely a curiosity until you've used these supposed insights to produce some form of verifiable evidence. Only then would one be justified in believing such a realm existed, let alone being named amongst those things which are known; that being the highest level of belief.
Regarding agnosticism - I would say that agnosticism is more an admittance of ignorance than an actual position. The only justified instance of agnosticism is one in which the individual recognizes that they are not informed, or perhaps not interested, in the evidence pertaining a subject.
In the case of mysticism and deities, since the actual subject is in fact the workings of our reality, I would suggest that all individuals are exposed to the evidence as much as anyone can be. The facts are, for the most part, staring us all in the face.
I am agnostic as to whether a fat woman lives in the apartment below me. I have no evidence, seek no evidence, and do not care about the answer.
I am an atheist because I am alive and I have seen the world and many of the things within, and I have yet to see anything which would reasonably lead one to believe that there are forces or entities outside the purview of science, both science known and yet to be discovered. Further, it seems simple to me to explain the belief in such supernatural phenomena by other individuals with the application of psychological theories.
Remember, the simplest explanation is almost always the correct one.
Furthermore, I tried to read Rand's Atlas Shrugged and found it absolutely unbearable. All of her main characters are totally contrived caricatures, invented solely to support her theories. People such as are portrayed in her novel do not exist. They are completely inhuman. More than just inhuman, in many ways repulsive; both "heroes" and "villains" alike.