Even the most accurate map does not show a city as it really is. Study a map of Istanbul, for example, before you go there for the first time and you will get a good idea of how the roads and avenues of that city are arranged, but nothing will prepare you for the reality of the place.
This is natural: no non-illustrated, two-dimensional representation can possibly portray perfectly a multi-dimensional entity such as a city of the size, area and complexity of Istanbul! All a map can do is give you an outline, an idea, an impression.
In the same way, even if we are given the most accurate description of God, until we actually experience Him there is no way that we can understand Him properly.
There is no `map' of God more perfect than the Quran, yet even with the Quran it is impossible to prepare ourselves fully for the reality of His being, or to understand Him as He really is.