The most important reason anyone is an atheist

[Little Rik]

That doesn't make any sense. Give examples. Don't just say things are "not working" thus-GOD. In your analogy we can easily understand what's wrong with the horse. There is evidence. Prove that people have souls, and marshal out your evidence that some people are weaker due to theirs having a lack of nourishment. If you can't do that, your analogy fails to be useful. Remember, it has to make sense to everyone. Not just you.

If peace of mind and total and permanent happiness could be achieved physically or mentally then we can say that nothing else is needed but as we know that is not possible that is why we need something else and that things able to give peace of mind and happiness is located within.
Many people say that they are ok or happy enough but that is not true.
If it is true they would not seek changes in their lives.
Have you ever seen anybody happy and content with what they have?
Go and find these people and then let me know.
It is part and parcel of human nature to change all the time until they reach the very top of human emancipation.
Not many people understand this point but whether they understand or not they are driven to reach the top.
A drop of water will keep on going towards the ocean and only when will reach the ocean she will become the ocean herself.
Human being whether they like it or not they driven by a mysterious force and this attraction will ultimately lead them in the big ocean of cosmic consciousness.
It is by resisting (not feeding the consciousness) that imbalances pop up and life become harder and harder.