Spiritism is not actually a separate, distinct religion. There are no churches, no dogmas, mysteries, rituals, or initiations, and there exists no priestly or minstrel hierarchy. At the same time, however, the spirits who brought us the teachings of the doctrine did not come to destroy religion, but rather to reveal to us still undiscovered laws of nature… and to prove, by demonstration, that which traditional religion teaches- in theory-about the soul, the afterlife, compensation for Earthly miseries of this world, etc. 

These revelations and proofs lead those who were previously in doubt to understand, with a rational faith, the true nature of God's laws, and thereby instill in them the will to seek reform- both personal and societal. So rather than constituting a distinct religion in itself, Spiritism is, rather, a philosophy with moral consequences. 

The fundamentals of this philosophy are based on, as stated by Pedro Barbosa in the book, Espiritismo Basico (Basic Spiritism): the existence of God, as the supreme intelligence and cause of all things; Evolution as the general law to which everything is subordinate except for God himself; Reincarnation as the predominant factor in divine justice;  and in the exercise and results of the use of our free will." 

As Kardec said then, "We can consider The Doctrine of Spiritism in its Religious aspect when it establishes a moral tie between men, leading them in the direction of the creator, through the application of the moral teachings of Christ." 

The moral consequences of the Spiritist philosophy arise when we consider our responsibilities as spiritual beings on a path of moral and intellectual evolution. We start out on our journey of evolution, ignorant and simple-minded, on a mission to reach a state of purification in which we have a complete knowledge of divine laws and a pureness of heart that commands our behavior. This purity, however, can only be achieved through great efforts toward personal growth, exercised over a series of numerous incarnations, through which we eventually learn to consistently demonstrate all the moral qualities that are characteristic of pure spirits, qualities such as compassion, forgiveness, honesty, selflessness, humility, resignation, etc.

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So, if Spiritism is not a new religion, do we need to follow one of the traditional religions? And if so, which one is best? People often asked Kardec these kinds of questions, and he would tell them,  "Follow your heart."

Spiritism does not prescribe any religion, nor does it discriminate against the followers of any religion. Likewise, it does not impose its own beliefs anyone. It simply reveals truths about the material and spiritual worlds, at the same time fulfilling the moral and spiritual needs of man in a practical and rational manner, and it will be found and followed by those who are seeking its knowledge. 

If you're looking for what's best for you, keep these words from Kardec in mind:
 "The best of all religions is that which:
- teaches only what is in accordance with the goodness and justice of God; 
- presents the greatest and most sublime idea of God and does not debase Him by attributing to Him the weaknesses and passions of humanity;  
- helps men to be good and virtuous and teaches them to love one another like brothers;  
- condemns every evil done to a neighbor; does not condone injustice under any pretext;  
- teaches nothing contrary to the unchangeable laws of nature; is led by ministers who set the best example of goodness, charity and morality;  
- combats best and flatters least the pride and vanity of men; and finally,  
- one in whose name the least evil is committed.  
A good religion cannot serve as justification to any evil whatsoever; it must not leave any door open to evil either directly or through interpretation.  Look, judge, and choose!"

Kardec, Allan. "I Have Not Come To Abolish The Law." The Gospel  Explained By The Spiritist Doctrine.  Trans. Allan Kardec Educational Society (translated from 3rd edition in French). Philadelphia, PA. Allan Kardec Educational Society. 2000. 26-29.

"Esclarecendo Duvidas" [Clearing Doubts]. Reformador. Rio de Janeiro-RJ, Brazil: Federação Espírita Brasileira [Brazilian Spiritist Federation].1987

Barbosa, Pedro Franco. "Postulados e Ensinamentos" [Postulates and Teachings]. Espiritismo Basico [Basic Spiritism]. 3rd ed. Rio de Janeiro-RJ, Brazil: Federação Espírita Brasileira [Brazilian Spiritist Federation].1987. 96-112.

Kardec, Allan. "Chapter Title if necessary." Christian Spiritism (a compilation of two Kardec books: Spiritism Reduced to Its Simplest Expression and What is Spiritism).  Trans. Allan Kardec Educational Society (translated from original French editions, published 1860 and 1859, respectively). Philadelphia, PA. Allan Kardec Educational Society. 1985. 106.