I only wanted to add to Magister Rose's clear answers that group ritual usually serves more of a ceremonial function than one involving magic. The ceremonial function is often intended as much as self-reminder of Satanic principles as it is a declaration of intent in a social setting.

Both have a special power in their own way.

You never need do anything you do not wish to.
_________________________
DISCOVERING THE SATANIC GOD
The Achievement of Infinite Self-Esteem
Nemo on Satanism - an mp3 audio program

THE FIRE FROM WITHIN

Nemo On Satanism: Volume One
Satanic Sources - Print

My 9sense interview on Greater Magic:
http://youtu.be/PCcYWmeSkCI