The answer will be the first one
Athens wanted to become the most powerful city-state in Greece. Sparta and its allies felt threatened by Athens's growing power.
It could have obvious dramatic effects, if a religious basis for ranking would differe substantially from the current social one, many things might happen. Imagine a reiligious ranking, ranking the lowest levels of people in a certain society to the the most valuable - it is very questionable what might happen.
It's a guess, but I think it's because the acts violated their rights to secure their home and trial by jury.
