Why god is not real in my opinon

[Undeceived]

how do you know that the 'brain' is not just the physical link between our souls and our bodies?

What sort of evidence is there that hints that it is?
Why would anyone think that it is?

There is the conceivability argument, the divisibility argument, and introspection argument, among others. The divisibility argument in a nutshell:

Descartes position on this argument is recalled by Lowe as follows: ‘This is that he, as a subject of experience, is a simple and indivisible substance, whereas his body, being spatially extended, is divisible and composed of different parts.’[5] This suggests that if we were to lose a part of our body that would not necessarily affect our mental states, purely our physical states. It seems to follow from this that if you were to say lose an arm in battle, you would like to believe that you were the same person before and after the amputation, regardless of whether your body was slightly different, suggesting that physical states must be different from mental states. If this holds true, then it would appear that a change in your physical state doesn’t mean a change in your mental state, which means they are two different substances and should not be identified together.

http://vincentwooding.wordpress.com/tag/...-argument/

Here's another thought experiment along the same lines. Suppose you get a heart transplant, lung transplant, frontal lobe transplant and so on until you have replaced every cell in your body. Are you still you? In the process of all the transplants, have you died at some point or continued to exist?