Let's be honest. The problem stated by the theists about moral relativism as the result of a godless world is quite valid. If there is no God, then there is no unifying set of principles that society can get behind, and everyone will become selfish and follow their own rules. Now, I do accept that our morality comes from within, not from external sources. But, still, won't everyone have different opinions of what our guiding principles and values should be? Will this lead to chaos and madness?
Simply put, will there be more or less selfishness in a world without God?
I think there will be less selfishness and here is why. First, the problem with religious conviction (most already know this): When you believe you are on the side of God, then even though you acknowledge that you are selfish, you begin to feel less so with time as you associate yourself with being on the "right" side of truth. You are a follower of the "right" team. You will then take steps to conform to your new unselfish belief system and you WILL make improvements in that area. However, after making some progress, you will start to believe that you are at least "better" than most people who are not part of your group and don't hold your values. As soon as this happens, you become arrogant and selfish again (from an objective perspective). But, not only that, now you are blind to your selfishness. To make matters worse, when the guiding principles of your group are derived from a source that is beyond question, then your views and behaviors also become unquestionable and uncompromising. Now, you have a reduced capacity to correct your perception enough to see your mistakes and correct them. Having a flawed perception is a problem for any normal person but religion exacerbates this problem and actually exploits this weakness for the purpose of the principle which, or course, is man-made and serves the purposes of an external controlling person.
On the other hand, in a world where everyone acknowledges their selfishness, anyone who follows a specific doctrine may be able to become closed-minded to other doctrines, but they will never be able disregard a sincere debate on correctness of their selfish behavior or guiding principles by using the typical conversation-killers based on religious conviction. And, most importantly, they will never be (less likely) able to stifle debates by claiming that their beliefs are inherently uncompromising, even if they secretly and privately hold doubts about their convictions. In short, they will be less likely to privately lie to themselves as well. The power of these kinds of conversation-killers comes from the power others give them and the social acceptance. Anyone who says that their view is correct because it comes from an omniscient deity would not be taken seriously anymore from that point on and probably be perceived as EXTREMELY selfish if not outright manipulative or both others and themselves.
Finally, in a mature godless society, in time everyone would be able to reevaluate their selfish desires and quickly realize that everyone has a lot of so-called "selfish" needs in common and that selfishness isn't such a problem after-all. Social pressures would still keep a check on certain extreme selfish behavior that infringes on others' rights. Even though society will still begin to focus-in on an exclusive set of guiding principles, they will not be of the uncompromising type that religious beliefs are based on. They will be more flexible and adaptable to a fast-moving future society.
A godless society is not anarchy. A godless society is just more flexible. Yes, things will be different and people will be doing some crazy things that you do not approve of. But, that has been the state of the world since the beginning. You still have the right to negotiate or even fight for your own selfish needs. Will there be chaos and rioting in the streets? Of course not. There are more people who will agree on common needs than those who disagree. The biggest thing that will change is that no longer will parents, governments, or cults be able to use brainwashing tactics to raise ignorant, powerless, and unreasonable slaves to their order.
And, for those Social Darwinists who think that anyone who is dumb or weak enough to become a victim of control deserves what they get, I remind you that the majority of the victims start off as children. Children are clueless and completely helpless to fight off the YEARS sophisticated brainwashing which, although sophisticated, are ubiquitous and easily mastered by anyone. A child is helpless and cannot defend themselves against years of lies, threats, and violence and all of the other mind games that go along with control and it takes YEARS to undo this conditioning. Let them grow-up with free and open minds free of religion and superstition and then see if they can survive your brutal world. The chances are there will no longer be such a brutal world because only those who can handle and live in reality will be able to survive and the liars are the ones who will not survive.
Sing