Just as any life, or 'world', is as good as another, ideas and beliefs are as good as another. There are no transcendent objective values set for us . . . Here again the idea that there is nothing important is repeated. Yet, we continue to live. So we must choose values and morals, realizing that they have no foundation and that one set of beliefs is as good as another.
Nothing justifies one or the other.
Therefore, our chosen set of beliefs are ours alone and not to be forced upon others. We have the freedom to choose. Yet, society can not exist without a base of common values and beliefs. So a set of rules have been created to keep people within the workable fabric of a society and a person's belief system is molded by the society. They do not have to accept it, but to disregard every rule would cause that person not to be accepted.