Spiritualism is not a religion. Spiritualism is the faith that we carry within the self. This could be the faith in a deity, a person, a belief or even the understanding that the sun is going to rise tomorrow.
Spiritualism is a way for the human animal to connect with the world around them. This includes not only those things of nature, but our fellow humans. Though spiritualism, we gain the ability to have faith and believe. When we have the ability to have faith, this can extend to the ability to have faith in what is considered impossible.
Many people today have religion, but they do not have the spiritual backing to create a strong foundation of their faith. Only though the spirit of what you have the ability to believe can you be a fully rounded and spiritual creature.