What I believe.
I believe that each one of us is one part god, and this is called many things in different cultures. Some call it the mind, some call it the universal consciousness, holy spirit, soul etc.
This consciousness, which from now on I shall refer to it as such, has always existed and has been permeating every living object on earth.
Take a self contained ecosystem. Imagine that we own a microcosm of life on earth. Nothing has to be done to feed this system, because it has all it needs to survive. The leaves withers, which decomposes to become nutrients in the soil which will be reabsorbed again by another living object. Things die and things grow without end within this glass jar. Everything gets recycled and reborned. That essentially is the buddhist way of understanding life.
Now, the idea of karma would mean that whatever you have done in this life, when you die, would bring about consequences down the line. Again, in the ecosystem, if I added a drop of arsenic into it, down the line, the living creatures in this system would suffer albeit not knowing how they would. That Arsenic is exactly what bad karma is all about.
The reason why karma doesnt exist in this system is that the living objects are not conscious. They have no divine spark in them even though they are alive. We however, as humans, have this consciousness which allows us to affect live in future generations. Therefore, being 'bad' in this life would mean poisoining consciousness with spiritual arsenic, causing more suffereing down the line.
Moreover, since this consciousness does not leave when we die, some of it remains with the soul that leaves the body. When the soul is ready to return as part of a living thing, the spiritual trauma / happiness of the past life would remain etched in this new living thing.
Everything essentially gets passed around in this life on earth, especially emotional impacts. That is why love is to be preached everywhere. That is why love rules all. Every religion claims it so though followers do not understand this fundamental idea.
Love covers all sins, covers all spiritual arsenic, and lifts humans up to a higher level. Those who truly understand the meaning of these words will ascend into heaven, never needing to participate in this process of living and dying, because he will be at one with the creator, whom was him and part of him since eternity.
