1) christianism was at the core of feudal hierarchy, with the divine right of the kings and the chain of beeing

Far from an exclusively Christian idea, this was in fact a pagan concept which the Christians strongly opposed for centuries. Pagan leaders had always ruled with divine right and in many cases were considered gods themselves. Two very basic examples would be the Roman and Japanese empires. After the collapse of the Roman Empire, the resulting political disintegration and decentralisation also greatly marginalised the Roman Pontiff, so most Christian kings retained both their profane and sacral leadership, as they had during paganism. The Popes were opposed to this, not in favour of it, which is one of the reasons for the strife between clergy and aristocracy, as well as the major conflicts between the Papacy and the Holy Roman Empire.

2) Christianity self-identified himself with the god-driven conqueror.

No idea what this is supposed to mean.

On the other hand, there's no religion on the earth that says "the strongest has all rights, the weak must be slave" because is severely disfunctional once you get over the initial conquering phase and you need to establish an actual society.

That's not the point. Every system has to achieve some sort of harmony. The primary values are what's important. In Christianity, this value is mercy. It is a salvation cult. Everyone is fundamentally broken, hopeless, insufficient and incapable of achieving salvation on their own. Even referring to the ultimate goal as "salvation", in contrast to enlightenment, for example, already hints as to the character of the religion. From the Christian perspective, every man - regardless of his personal qualities - is weak and helpless, entirely dependent on mercy and salvation. Does this reflect an aristocratic wolrdview, in your opinion? If not, what worldview does it reflect? It's a downward looking religion. Everyone needs to be saved, but no one can be saved by his own efforts. The responsibility of saving human souls is laid on god, the responsibility of saving humans is laid on the aristocracy. What does this mean for the aristocracy? It means that its justification becomes entirely external and "humanitarian". The higher depends on the lower for its meaning, rather than vice versa. Hence "slave morality".