If the soul is not purified then large amount of spiritual energies can harm us because they tend to activate dirty energies that we have inside. Master Choa Kok Sui teaches that dirty energies come from two main sources. Outside sources and inner sources.
Outside sources are food we eat, water, air and other negative influences that come from outside. Inner sources come from us and are negative emotions, words and actionss toward others and towards our self. Master Choa Kok Sui called this character building. So when practitioners purify themselves with time soul becomes more purified, larger amount of spiritual energies can come in and higher degrees of spiritual development become possible.This why in every serious spiritual practice they have strict rules what to eat and how to behave.
So when we meditate and do our spiritual practice properly(which includes purification) we actually become better people or to be more precise better servants of divine. This ensures that we don’t just get our freedom but we also help others survive, have more beautiful lives and reach spiritual freedom as well.
In higher degrees of spiritual development we reach a stage of expanded consciousness also known as nirvikalpa samadhi in Indian tradition that I have described before, when you are in a constant bliss all the time. Then after a body dies you continue your journey in a spiritual world and don’t have to incarnate on the earth again(at least for a long time). This Is because you have fulfilled what you came on earth for.
If you are interested in more information check out these books . They explain all of this in very simple manner and allow a person to understand this in an objective, scientific matter and confirm all of this with simple experiments. “Miracles through Pranic Healing” and “achieving oneness with a higher soul” .