Just when Lord Buddha found his enlightenment under the famous Bodhi tree, Buddhism found its birth, and it is since that day, Buddhism started spreading across the boundaries. In fact, Buddhism not only started spreading, but was evenly divided into multiple sects, and adopted in numerous beliefs, rituals, practices and even customs. Even though there have been diverse things accumulating under one umbrella, it all unified in Lord Buddha.
It was much later in 1866 when some of the renowned monks met in Sri Lanka and decided that all these diversified groups need to find harmony and bridge all the differences that existed between them. So identifying the terms of agreement turned out to be the most important aspect of this meeting, and once it was done, Buddhism preached only one message. Even Soka Gakkai Buddhism is not beyond these understandings and agreements. Lord Buddha was the only master accepted in unison and they had to take refuge in him, the Dhamma and the Sangha. And nothing in this world existed beyond these three.
However, the way rest of the religions look at human lives is quite different from how Buddhism looked into it. Buddhism has always had an overview of the human life in five segregated parts, or more popularly known as the khandas:
According to Soka Gakkai Buddhism, which is no different than its purest form, all these individual khandas come together and help in the formation of a human life. A person is a complete individual identity, and in his complete being, his actions or karma has got a huge role to play. But does the soul change along with the actions? No, it is the purest form and stays so even during the journey.
The doctrine of Annata, which when camouflages with the Buddhist concept of reincarnation and Karma, comes up with a major confusion. It says that if human beings have got no soul of his own, then what actually does it reincarnate, and into what? Now, a major section of these beliefs and ideas that mankind had no soul in them was based on speculation, and hence lacked solid proof.
Lord Buddha never believed in speculation and was even completely against it. Just like any institution finds easy opponents in its course of formation, Buddhism had its own as well. They never delayed in pointing out the vulnerability in the concept of Buddhism and started raising voice and all kinds of opposition that was possible.
Buddhism had a nice analogy in their record to give these oppositional forces a suitable answer. When a candle is being used to light another, the new flame that takes birth is definitely different than the old one; however, the presence of the first one cannot be neglected in the formation of the second one. So is human life, one action leads to another and one life to the other as well.