While no statistics are available, I've noticed that over the last twenty years, more and more people have been changing their names--those vital shorthand tools for knowing and being known--for spiritual reasons.
The custom has ancient roots in religious traditions. Popes take new names on their election, as do nuns and monks when they enter the religious life. Roman Catholics add a name at confirmation, Jews have Hebrew names used in religious services, and Zoroastrians change their names at critical junctures in their lives. So do many people in non-Western traditions at life transitions such as adulthood and marriage.
Lately, with roll-your-own spirituality on the rise, the appellation game has taken on new dimensions. Some successful professionals alter the spelling of their names or add a middle initial based on numerology.
Neo-pagans sometimes chose a new name--often only one, eliminating the family name to show that they have embraced a new community--and change it legally to suit their new religious beliefs. They may take a name from mythology, such as Thor or Venus, inviting the attributes of the god they want to emulate. Or they name themselves after the sacred trees of the druids--Oak or Ash, hoping to share in the magical properties of the trees. Some invent names--Rain Warrior and Black Snake Woman--that tell the world how John Smith and Jane Doe want others to see them in their new beliefs.