Just read this and tell me what you think.

[Jenny A]

It is extremely difficult for me express my thoughts into writing but I will try my best.

Right, atheists believe there is no life after death, no supernatural being or world and so on.
Their belief is based on the laws of Physics.

Some atheists believe that there are no god or gods.  All atheists lack a believe in a god or gods.  This is subtle but important difference.  Regarding the truth of any claim there are three possible positions:  proven, disproven, and unproven.  With regard to god, atheists include those falling into either the unproven and disproven groups.

Atheism only concerns a lack of belief in a god or gods.  It is quite possible to be atheist and believe in an afterlife, or other supernatural ideas.  

Their belief is based on the laws of Physics

Nope.

All information we receive is through our five senses, which is then processed in our brains, which also affects our understanding and thinking.
So we know that our brain is responsible for the way we perceive this world we live in.

Actually there are considerably more than five senses, but we'll let that pass for the moment. http://listverse.com/2013/04/30/10-lesse...an-senses/

With certain substances (for example DMT) our minds can be 'altered' where we now live in a completely new world. This new world does not obey the laws of physics. We meet and interact with other beings. The time we spend in this new world is as life like as any.
My thought is, how can we be so sure this new world is only an illusion and not real? The information we receive in this new world is still being processed by our brains, just as though it is right this moment whilst you are reading this post. The brain is the same, the only difference is the way your process the information you receive.
The time we spend in this new world with an 'altered' mind although relatively short; still exists as you have seen and have been in this place.
If you were living in this new world with the 'altered' mind for longer than a few hours, say few years, would you not believe this new world as your only world?

How do you know right this moment whilst you are reading this post your mind is not 'altered' from a time before you were born on this planet?

The brain naturally produces DMT, at three points, a large amount when you are born and when you die, and a small quantity whilst you are dreaming.
This adds to my point, if you were to take DMT right now, you will be transported to a whole new world, the way you perceive information is now completely different to what has been since you have lived. So.. when you are born DMT can be seen in the brain in large quantities.. and when you die DMT can be seen in the brain in large quantities. Can you see the link?

Edit: By a 'new world' I don't literally mean, you physically locate yourself to a whole new world, I mean that the way you now perceive things are so different to how you 'normally' do, that you see and are in a whole new world (in your mind). The new place you see is so life like that you believe this is real whilst the time you are there. The only difference is the way your brain processed the information it was receiving. However at the time it feels just as real as it does right now while I am sitting here typing on my computer.

Drugs, hormones, sleep states, brain trauma and a number of other things can alter perception and thinking.  Proving that I'm not in one of those would be difficult.  But behaving as if I thought I was would lead to much greater consequences.  Generally speaking we all behave as if we are perceiving the world correctly because bumping into walls hurts.  In other words it's counterproductive, and impractical to waste much time worrying that we are under the influence of a drug or part of a matrix like computer program etc.