The basis of all Judeo-Christian scriptures is the Hebrew letters. Without an in depth knowledge of the Hebrew letters, the original language of the scriptures, one cannot understand the Western religions or the secrets hidden within them. Like Sanskrit, Chinese, Tibetan, Greek and other ancient languages, the Hebrew letters constitute a primary expression of the language and mathematics of spirituality. In scriptures, dreams, and awakened experiences, the symbolism of Kabbalah is delivered through the Hebrew letters. This is the language of the internal worlds. Learn to speak the language of the internal worlds, Kabbalah, by first learning the letters of the language.
"The objective of studying the Kabbalah is to be skilled for work in the Internal Worlds... In Kabbalah we have to constantly look at the Hebrew letters." - Samael Aun Weor, Tarot and Kabbalah (1978)
Here are some articles, books, and courses to get you started: