Before we dive into Mysticism proper, lets explore how the human brain/mind works. This is important to know because some religions understand God in a logical way and other religions are more intuitive or inspired in their knowledge. This will especially help us to understand God from a Buddhist or Taoist perspective.
The left brain is a world of business, logic, reason and of practicality. The right brain is a world of art, emotion, intuition and of feelings.
The left brain requires logical, linear, factual data to be satisfied. The right brain is more comfortable with leaps of faith, inspiration and intuition.
To better understand God and how God is communicated it helps to understand that the brain/mind operates and functions on these two levels and through both we can achieve a more complete understanding of God.
The best example of a right brain religion is Tao. Tao is nonsense to the logical western mind. Yet Taoism is a great sourse of mystic knowledge.
Judaism is an example of a left brain religion. Ten commandments, Holy Days, clean and unclean meats, etc... The logical mind understands rules and regulations and Judaism is a very structured ordered and logical religion.
All of the other religions are somewhere in between with Islam being almost as logical as Judaism and Buddhism almost as right brained as Tao.
Hinduism and Christianity are balanced in the middle with Hinduism slightly more right brained and Christianity slightly more logical.