Spiritualism is said to be a Philosophy, a Science and a Religion. Below is a short summary of each of these characteristics.

Spiritualism is a way of life. It combines philosophy, science and religion. It covers a very wide field, and, therefore, you cannot expect to understand it without a certain amount of study.
Spiritualism very much accepts the natural laws of the physical world to be that which man lives within and as such he cannot do anything outside these laws. The primary object of Spiritualism today is to prove the survival of human personality after death. Death is the doorway to a new and wider life. From the day of our birth we each have a number of bodies, two of which are the material or earthly body, which can be seen, and the spiritual body, which is unseen with physical eyes but is a counterpart of our earthly body. These two bodies are linked by what is called 'the silver cord'. When we die, the silver cord is severed. The material body returns to the earth whence it came, and the spiritual body becomes the vehicle of our spirit. We are actually spirit here and now - we don't have to wait until death to become spirit. Death, as a rule, seems like sleep - there is no pain after passing. When we awake, conditions seem much the same to us as before we "died". We take with us into the beyond no material possessions, such as clothes or money - they are no longer needed. But we do take our character, our experiences and our individuality. In every way we are the same individuals immediately after death as before, with all our good traits and faults. The home that awaits us in the spirit world depends upon the life we have led on earth. If we have honestly tried to do the best we can and been just, fair and of service to ourselves and to others, then we need have no fear of death. We are ready for a better, happier life. Here we are reunited with our loved ones and friends. If, on the other hand, there has been more selfishness than goodness and service in our lives, we will automatically find ourselves in a place which is not happy and probably in company with others who have shown similar negative personalities. This is part of the law - 'as you sow so shall you reap', which is only another way of saying that effect must follow cause. This is perfectly summarised in the sixth principle below, which says that hereafter there is compensation or retribution for all the good and evil done on earth. Acts of service that we have performed will naturally increase our spiritual status. Sins of omission or commission will just as naturally retard it. There is however no hell in which its inhabitants are condemned for eternity. Once self-realisation dawns and the spirit is ready to advance, there are enlightened spiritual beings who will show the way to progress. The practical application of Spiritualism is the supreme necessity for all of us to lead the best kind of life we can on earth, to practice qualities of compassion and kindness and to give service wherever we can. The traditional heaven and hell are really states of mind, not geographical or heavenly locations. Even here we can live in heaven or in hell, the choice is ours. The world we inhabit after death is not far away up in the sky. It is around and about us, interpenetrating the world in which we now live. Those we have "loved and lost awhile" are not in some far off, inaccessible place, seated on pink clouds at the right hand of God and playing golden harps. (I don't know about you but I cannot play a harp). Very often, they are close by our side, striving to help and guide us, and loving us just as they did before passing to spirit. The evidence given by mediums from spirit people reveals that love, like life, is stronger than death. It is love that proves to be the compelling force, striving to break down the barriers, which humans in their ignorance have created, between this world and what is called the next, in order to achieve spirit communication. Often there is grief on both sides of the veil. There are the tears shed over loved ones who have died and the grief they experience when they try to reach us but fail to make their presence known. There are many spheres of existence in the spirit world that are invisible to us because they exist at different levels of 'vibration' from earth. Millions of vibrations of sound and sight are lost to us because they are outside the range of our seeing and hearing and scientific detection. Just as microphones and radio receivers enable us to hear what is normally beyond the range of our ears and the telescope and television bring into focus what is beyond our vision, a spiritualist medium can demonstrate to us that the inhabitants of the spirit world are very real even though we cannot see or hear them. Mediums are highly sensitive individuals who have developed their innate natural psychic faculties with the result that they can attune to the spirit world and its inhabitants. Mediums become the agents through whom spirit communication is achieved. There is nothing supernatural about mediumship. Everything in the universe is in accordance with natural laws. God - the creator and source of all that is, is spirit and Spiritualists usually call him/her 'the Great Spirit'. Traditional notions of God being an old man with a long white beard who sits on a throne in heaven are mistakes. To picture God as male or female human being is ancient thinking. God is not a person but is universal spirit. Wherever there is life there is spirit; and wherever there is spirit there is life. We exist because a spark of divinity is within and all around each one of us. This is a divine relationship in which the Great Spirit is our father/mother and we are all His/Her children. We can fan this spark into a flame so that our lives express a greater amount of divinity. The result will be to sustain, uplift and help us in our spiritual development; and we have the free will to neglect, reject or ignore the spark of divinity. The result will be that we fail to make the progress and deny ourselves much of the beauty that life has to offer. We do not believe in saviour Gods as preached in some orthodox religions. The idea that someone else may be punished for our misdeeds we see to be quite wrong and repulsive to anyone with a sense of justice. We are each personally responsible for our good and evil deeds and must bear the consequences for them here or hereafter. We do not claim to know everything - no one does. Knowledge is infinite and we shall always be learning. What we do maintain is that we have caught a glimmer of truth. It inspires us to search for more, rejecting anything that does not appeal to our God-given reason and accepting that which is logical and uplifting. What makes Spiritualism unique is the evidence of survival after death that is obtainable through mediumship and personal experience. Whereas most religions preach an after-life as a hope, faith or belief, we maintain that any reasonable person can prove it for themselves and have sure knowledge of this truth. We do not ask you to believe what we say.
What we do suggest is that you study the evidence and then investigate yourself.

Spiritualists don't have any fixed doctrines but most agree on the traditional seven principles:

1. The Fatherhood of God.
(The energy that permeates all things and is the source of everything)
2. The Brotherhood of Man.
(We are one yet we are individual)
3. The Communion with Spirits and the Guidance of Angels.
(We communicate with those in the spirit world and the Angels ensure we stay on our chosen path)
4. The Continuous Existence of the Human Soul.
(The essence of each one of us continues eternally after physical death)
5. Personal Responsibility.
(We are responsible for all our thoughts, actions, feelings and all that exists)
6. Compensation and Retribution Hereafter for All Good and Evil Deeds Done on Earth.
(Nothing we think, feel or do goes unrewarded or unpunished)
7. The Path of Eternal Progress is Open to All Who Wish to Tread It.
(The progress of our soul is available to us for all eternity)

Spiritualism is considered a science because investigation to the nature of and phenomena within Spiritualism is possible and has been carried out for many years especially in the late 1800s and the early 1900s. Particularly in the years mentioned many Spiritualist and other groups conducted 'circles' for the production through spirit agency of Physical Phenomena. This phenomenon was of a number of different modalities for example:
Direct Voice- Direct Voice was the production of voices without the use of the actual voice box of the medium present. Voices could be clearly heard within sometimes a very large room from a distance and typically a top corner of the room near to the ceiling. A person could be sitting close to the medium and clearly be able to detect that the voices were not coming from the medium. A case of this was where an aircraft hangar was used and microphones were positioned in the top corners of the building. A direct voice medium sat in the centre of the hanger. Recordings were made of voices that were picked up by the microphones but were not audible to the people in the group and were confirmed as not having originated from elsewhere. Scientists have complained over the years, that Spiritualist phenomena could not be proven because they are often not repeatable in experimental fashion. Well this was one experiment that could be repeated and other direct Voice experiments produced the same result. There were a number of very famous direct voice mediums and one such was Leslie Flint.
Apports - Apports are objects which appear in a group without being physically moved or relocated. Objects , nearly always small in size, were experienced as being apported such as flowers, feathers, small artefacts like crosses, semi-precious gems and stones. If a table was placed in the centre of the group the objects would just fall on to it. This of course, without the strictest vigilance and security measures, was easy to fake but many cases of what was deemed to be genuine phenomena were recorded.
Materialisation - Materialisation is a phenomena achieved by the production from the medium within the group of a substance known as ectoplasm. It is a combination of spirit energy and substance with physical energy and fluid or substance from the medium and the other sitters. By appearance it varies greatly but has been said to be like cotton wool or milky mist. In the group it often is seen to run from the mouth or nostrils of the medium and then run across the floor. At a distance from the medium the substance clumps and often a head is formed which gradually rises as the body forms until the materialised body of a spirit is present. Such materialised forms can speak and sometimes touch the sitters and often are clearly recognised as loved ones who have passed to spirit by the sitters. This is probably the most difficult phenomena to repeat in scientific experimental conditions but has been recorded by reputable people on thousands of occasions.
Scientific Testing - Many Mediums were tested by scientists during the past century and a half and in many cases the scientist would construct a simple mechanism where for example a lever was supported by a spring balance. The test would be for the medium to put weight on to the spring balance through the lever without physical contact. This was achieved on many occasions under the strictest of conditions. We maintain that the tenants of Spiritualism have been proven in these ways countless times.
Religion - After the inception of modern Spiritualism it very quickly developed into a religious practice. Initially some parts of the orthodox churches in the United States saw the contact between the two worlds as being a demonstration from God of deeply divine manifestation. Although this perception did not last the people within spiritualist groups surrounding mediums continued to develop a religion without the cruelty, persecution and control of Orthodoxy. Spiritualism sees the continuation of human spiritual life and loving experience demonstrated by mediumship in its churches every week as proving not only the essential spiritual nature of man but the ever-present love of the Great Spirit in all of our lives. The seven principles given above show God as a loving parent protecting, guiding and supporting each one of us and we believe this is the very essence of true religion