The custom of substituting the word "God" with G-d in English is based on the traditional practice in Jewish law of giving God's Hebrew name a high degree of respect and reverence. When written or printed, God's Hebrew name (and many of the stand in names used to refer to God) cannot be erased or destroyed. (See below)
There is no prohibition in Jewish law against writing out or erasing the word "God" in English. However, many Jews have afforded the word "God" with the same level of respect as the Hebrew equivalents. Because of this, many Jews substitute "God with G-d so that they can erase or dispose of the writing without showing disrespect to God. Some Jews also use G!d in the same way, utilizing the exclamation point to convey their enthusiasm for Judaism and God.
Hebrew Names for God
Over the centuries the Hebrew name for God has accumulated many layers of tradition in Judaism.
- The Ancient Name of God: The Hebrew name for God, YHWH (in Hebrew spelled yud-hay-vav-hay), is never pronounced out loud in Judaism. When it appears in Jewish scripture or liturgy, the reader substitutes the Hebrew word "adonai" which means "my lord" or often just "the Lord." Any book that contains this name written in Hebrew is treated with reverence. The name is never destroyed, erased, or effaced and any books or writings containing the name cannot be thrown away according to Jewish law. They are stored in a genizah (special gathering place in a synagogue) until they can be given a proper burial in a Jewish cemetery.
- Adonai: Among many traditional Jews even the word "adonai" is not spoken outside of prayer services. Because "adonai" is so closely linked to the name of God, over time it has been accorded more and more reverence as well. Outside of prayer services, traditional Jews will replace "adonai" with "HaShem" meaning "the Name" or some other way of referring to God without using "adonai."
- Other Names to Refer to God: Because YHWH and adonai are not used casually, literally dozens of different ways to refer to God have developed in Judaism. Each name is linked to different conceptions of God's nature and aspects of the divine. For example, God can be referred to in Hebrew as "the Merciful One," "Master of the Universe," "the Creator," and "our King," amongst many other names.