Christianity results in stagnation because it depends on one single book.

Then why it actually evolves?
Why there are and were so many branches, so many reformations and reformations of reformations?

Why did Christian peoples evolve so much in the last millenium?

because they have been taught to hate it because it was sinful, so no one has a problem with destroying that what they need to survive

How were we taught to hate it?
And I do not destroy what I need for survival, because then I would hardly survive :)
If you meant destruction of nature, guess how the deserts of Near East came into being? And that was way before Christianity.

Modern world, id est industrialized world, will fall

That is certain. The question is, when and why it will fall.
In X-thousands years because of a huge asteroid?  :D

Concerning selfishness, hedonism and other decadent things. Pagans were not selfish because they needed their families to survive. They were not hedonistic because they hadn't any time to do that.

Increasing hedonism is a sign of advanced civilization. Sociologists may better describe its purpose, I am still in a stage of thinking about it. Selfishness is a normal human trait, often crucial for survival. Selfishness of an individual may be important even for survival of a group.

Pagans of old were selfish as any human being, and… hedonistic? Please! Romans, Greeks, Persians, Indians (Kámasútra  ;D ).

our forefather have been anything else then primitive

IMO my ancestors that lived 20 000 years ago were quite primitive.
Unless they came from Mars 10 000 years ago  :D

A tribe holding on to it's culture and morals does not want to develop and get better so that they can f*ck around and be selfish, this is not the aim in developing

A tribe that does not develop will fall prey to those who develop, sooner or later. Nature is cruel.
Explain how developing is not the aim of developing. Because that is what you practically imply  ;)

they don't throw away their culture because their culture always helped them surviving, giving them mental strenght to develop the right way. They develop WITH the culture, not against it. This is the difference. The modern world didn't develop with culture, with nature, but against it, and so it will fall.

Nonsense. Culture evolves together with people. Saying that some people evolved against their culture is analogous to saying that my hand evolved against my fingers.

And countless times people abandoned their older culture in favour of another one. Often in order to have an advantage in survival. It is called [cultural] assimilation.