Bogomilsm was based on Persian dualism: the master of the spiritual world was god, and the material, which was transitory, was ruled by the evil god Satan. The same principle is evident in Christianity, Islam and Judaism where the principle of good and evil are clearly accentuated, and that god for various reasons never managed to defeat Satan and that's why both of them have their kingdoms and eternally opposed armies. The balance of power is equal with a religious promise that Satan will be eventually beaten and destroyed.
The main element of the spiritual world was the soul, for which the Bogomils believed that with migrations or metempsychosis it aims at eternal perfection or nirvana - final liberation. According to Bogomil doctrine, it was forbidden to kill animals and birds, and even to destroy their eggs, because in every animal there can be a human soul doing penance for the sin's a man has done for his lifetime. That old Bogomil beliefs left a huge mark on the Bosnian people is best witnessed by the still active belief from north-western Bosnia which claims that evil people turn into animals after death such as pigs, cows, horses,. in order to serve humans in their new life and to pay for their sins.
One important record, which dates from the Ottoman occupation of BiH, named "From Bosnia with pictures" speaks explicitly about the very widespread idea of reincarnation among the Bosnian people. Author Clement Božić commented, like numerous other contemporary observers, seeing packs of dogs moving freely around the neighbourhoods and streets of Sarajevo: "Bosniaks take care of them (dogs), by giving them complete freedom; they say that some of them may contain a human soul and if someone has a bad dream, in the morning they buy bread and feed them to the dogs."
The only animal that cannot have a human soul is the snake, probably because of the Illyrian legend according to which a snake has been created 40 years prior to any living being on this planet. This mythological belief of the Bosnian people is completely analogous to the ancient representation about the forefather of all Illyrians which was wrapped by a snake when he was a baby. In many ways a snake has been officially given a favoured status and she had a special place among the Bogomils which can be seen from numerous legends created throughout the Middle Ages where this animal plays a major role. To the Bogomils, unlike other Christian churches, the snake didn't represent the reincarnation of evil since according to their doctrine the tree of knowledge of good and evil was a woman (Eve), and Adam sinned for copulating with her, and that's why both of them were banished from heaven. Thanks to this fact the existence of the cult of snake was never brought into question throughout any period of Bosnian history, not even during the turbulent Middle Ages. The answer to the question why was only the snake exempt from the karmic circle is that she as a holly animal cannot be the bearer of a human's sinful soul, her task is to use her mystical powers to protect every house and all souls living in them.
Even though the Bogomils weren't inclined, according to their religious belief, to excessive indulgement of earthly goods, they were, like all others, exposed to constant temptations which ruled the evil material world which additionally made it harder for a soul to achieve enlightenment. According to Bogomil's conception the end of the reincarnation cycle was only possible after receiving the sacrament at death with which the soul would achieve its spiritual regeneration. It was only possible through this type of cleansing and after separation from the material world which was under the control of evil. The final goal was to ensure the unification of the soul with the good god. In a lawsuit in Torino in 1388 a claim mentioned that a soul which doesn't receive consolamentum transfers into the first body to which it comes across to, either human or animal; this continues on until it is blessed by its spiritual father on its deathbed.
When we summarise all that has been written so far we come to some sensational data which reveals to us that in Bosnia and Herzegovina we find very clear and evident basic doctrines about karma and reincarnation which can be considered to be rare, if not the only country in this part of Europe, with such traditional concept which certainly didn't form in the Bogomil religion, but it's appearance dates from ancient times. That's why this particularity deserves special research.
Reincarnation as a term was well defined in Bhagavad Gita, authoritative writing of a Vedic teacher which dates from the 5th century BCE, defined as a cycle of birth and death in the circle of samsara, and karma as causal effect according to which by our own actions, thoughts and feelings we create our own destiny. The idea about reincarnation can be found on all continents. But, for us the most important data is that reincarnation as a thought was present among the old Celts and Persians, two peoples which more or less had a defining influence on the religious understanding of the Bosnian people, especially during ancient and middle ages.