What are some of the core tenets of Scientology?
Fundamental to Scientology is a view of Man as a spiritual being. In Scientology, the spiritual being is called the thetan . The term is taken from the Greek letter theta for “thought” or “life” or “the spirit.” It is used to avoid confusion with previous concepts of the soul. The thetan is immortal and has lived—and will continue to live—through countless lifetimes. One is a thetan who has a mind and who occupies a body. The thetan animates the body and uses the mind.
Also fundamental to Scientology is a view of life as compartmentalized into urges (drives, impulses) toward survival. These are called the dynamics  and number eight in all.
The First Dynamic—is the urge toward existence as one’s self. Here we have individuality expressed fully. This can be called the Self Dynamic.
The Second Dynamic—is the urge toward existence as a sexual activity. This dynamic actually has two divisions. Second Dynamic (a) is the sexual act itself. And the Second Dynamic (b) is the family unit, including the rearing of children. This can be called the Sex Dynamic.
The Third Dynamic—is the urge toward existence in groups of individuals. Any group, or part of an entire class, could be considered to be a part of the Third Dynamic. The school, the society, the town, the nation are each part of the Third Dynamic and each one is a Third Dynamic. This can be called the Group Dynamic.
The Fourth Dynamic—is the urge toward existence as or of Mankind. Whereas one race would be considered a Third Dynamic, all the races would be considered the Fourth Dynamic. This can be called the Mankind Dynamic.
The Fifth Dynamic—is the urge toward existence of the animal kingdom. This includes all living things, whether vegetable or animal, the fish in the sea, the beasts of the field or of the forest, grass, trees, flowers or anything directly and intimately motivated by life. This can be called the Animal Dynamic.
The Sixth Dynamic—is the urge toward existence as the physical universe. The physical universe is composed of Matter, Energy, Space and Time. In Scientology we take the first letter of each of these words and coin a word—MEST. This can be called the Universe Dynamic.
The Seventh Dynamic—is the urge toward existence as or of spirits. Anything spiritual, with or without identity, would come under the heading of the Seventh Dynamic. This can be called the Spiritual Dynamic.
The Eighth Dynamic—is the urge toward existence as infinity. This is also identified as the Supreme Being. This is called the Eighth Dynamic because the symbol of infinity, ∞, stood upright makes the numeral 8. This can be called the Infinity or God Dynamic.
Scientologists usually call these by number.
A further manifestation of these dynamics is that they could best be represented as a series of concentric circles, wherein the First Dynamic would be the center and each new dynamic would be successively a circle outside it. The idea of space expanding enters into these dynamics.
The basic characteristic of the individual includes his ability to so expand into the other dynamics. But when the Seventh Dynamic is reached in its entirety, one will only then discover the true Eighth Dynamic.
As an example of use of these dynamics, one discovers that a baby at birth is not perceptive beyond the First Dynamic. But as the child grows and interests extend, the child can be seen to embrace other dynamics.
As a further example of use, a person who is incapable of operating on the Third Dynamic is incapable at once of being a part of a team and so might be said to be incapable of a social existence.
As a further comment upon the Eight Dynamics, no one of these dynamics from one to seven is more important than any other one of them in terms of orienting the individual. While the dynamics are not of equal importance, one to the next, the ability of an individual to assume the beingness, doingness and havingness of each dynamic is an index to his ability to live.
The abilities and shortcomings of individuals can be understood by viewing their participation in the various dynamics.