Being agnostic really has nothing to do with religion. It simply has to do with being able to, or not, prove ideas. Rather, agnostics won't try to pretend something is factual when they cannot prove it. As the OP said, you can be theistic and agnostic at the same time, if you believe that God exists but you don't pretend it is a fact that you can prove. Since this is the case, agnosticism cannot be defined as a middle ground between theism and atheism.Agnosticism is not a creed but a method, the essence of which lies in the vigorous application of a single principle... Positively the principle may be expressed as in matters of intellect, do not pretend conclusions are certain that are not demonstrated or demonstrable.