In many countries nowadays (esp. in the west) secularism is touted as the most fair way to balance what groups of people believe is right and the truth, and the ruling over them by practical means. If you tried to implement different laws to different people a crisis would appear. Groups will gravitate to their own communities and set up their own "virtual mini-states" within the state.
This is obviously an untenable situation. Such a scenario would be ripe for fragmentation. So, what is required is some unifying system that everyone can agree on (or rather, agree to disagree on) so that a large community of people can be effectively controled and ruled over.
We see this applied in countries like the US, the former soviet union, Indonesia and probably in the future, Europe where there are numerous groups, many at odds with each other regarding this very fundamental problem of right and wrong and justice. And this needed "magic bullet" is seen as secularism. Basically, what it says is that, we agree to have our own beliefs but we shall keep that at a personal level and so should you. So, to keep us together, we shall agree on a system of law that is "fair" to you and to us. And this ruling system is invariably democracy, worldwide.
However, there are some very fundamental flaws in secularism and democracy. And this is the issue of right and wrong itself. The issue of fairness and justice. Who decides what? How do we decide? Each group in the state will have their own notions of right and wrong. For example, Hindus wont want to legalize eating beef . But liberals would. So who's right? In the secular system, we all have to agree to suspend our own (groups') notion of right and wrong and debate these issues together to come up with the laws that we will use to govern ourselves.
This is done in democratic nations in institutions like parliament, council of lords etc. Laws are proposed and debated and if the majority votes approve then it is passed or rejected if the opposite happens. So, what this means in practice is that, if your group is small, and your views are at odds with the majority, you will have to swallow the knife and suffer the indignities that result. If you want to stay on in that country of course. This happens to Muslim communities all over the world this very day.The problem with this is that, we must agree that all our beliefs share the same level of truth-ness. That is, even though my beliefs are different from yours, they are at the same level of rightness and importance.
So, in a secular democratic country (which every country seems to be falling over themselves to be) if it so happens that the group of Satanic Worshippers become the majority, then laws that are more inline with their beliefs will be passed in parliament! And all other groups will have to abide by them. Even if you are at odds with it.
So now we need to answer the fundamental question. Who truly has the right to determine what is right and what is wrong? According to secular views, it is Man himself since his beliefs are all 'equal' no matter how opposite they are. So no one single view from a single group should be taken since this would be unfair on the other groups. So only the majority's opinions would be 'fair'. However, here we come to the main problem. Is Man capable of the task?
To decide on laws governing humans, you will need tremendous knowledge about the human condition, mentality, human interactions and interdependence between each other as well as the environment and the nature of Man itself. Can we claim this? Even the best minds in all the related fields agree that our knowledge of those fields can only barely scratch the surface and never will really get the whole picture. So we try our best? Is this a fair and just course of action? Obviously not. Left to his own devices, Man will always follow his instincts and dream up all sorts of ways to satisfy them whatever the cost even if it is against their very nature!
Like what? Try homosexuality. It is totally against human nature. It serves no purpose whatsoever. Homosexuals cannot propagate the species, thats obvious. But, you see in the west, if you speak against this, you become the evil one. The 'bad guy'. You are the one labeled as intolerant and unfair! Such ridiculous situations can only arise when there is no set rules or basis for laws but where humans can make up their own.
What is right and wrong can change as time goes on - even though the nature of humans and their needs do not - as they have not in all human history.