Karma and Neurobiology

After studying a bit of neurobiology, past lives and concepts of soul seem irrelevant. Karma etc. also seem irrelevant. I am not saying that it is not possible (the probability is quite low), it seems irrelevant.

One of the things that bothers me is the lack of significant leaps in spirituality and religion. Why does god not reveal himself anymore? Why did he only choose to appear thousands of years earlier? I am kind of losing faith in religion and ancient philosophies.

I find most of the theories of karma absurd. Probably everything can be explained at the neurobiological level. What if a person becomes bad due to physical neurobiological damage? Should bad deeds accrue to his karma?

Are the majority of people deluding themselves? Reconciliation is such a herculean task.