During my religious phase, which lasted several years, and during the many years afterwards up to the present day as an atheist, I have tried to cultivate and abide by a moral code to guide my conduct. From my personal observations and experience, my interest in history, and my readings from various religious and philosophical texts, it became obvious to me that certain qualities in both individuals and society at large were beneficial if one values civilization. While acknowledging that I am a flawed human being who does not always live up to the standards he sets for himself, I took it for granted that overall I was a moral being and a good person.
It was much to my surprise then when approximately one and a half or two years ago a theist I had been having a back and forth with in the comments section of somebody's blog (I don't remember whose) told me that I had no standing to say that something was right or wrong because as an atheist my morality was subjective. In other words, I could only argue as to why I personally thought something was right or wrong and that my opinion as to why rape or murder was wrong was no more valid than another individual who might think that rape or murder was okay. The theist, on the other hand, took the position that since the god he believed in declared that rape and murder were wrong, his morality was objective.
Up until that moment, I don't believe I had ever heard that argument raised. Frankly, it struck me as rather ridiculous. Since as an atheist I did not (and of course still do not) believe in the existence of god, the theist's morals were just as subjective as mine. The difference between he and I was that my view of right and wrong and good and bad was a synthesis from various sources, while the theist derived his view of right and wrong by buying into an already prepackaged belief system that purported to offer an objective standard of right and wrong.
I would sum up the difference between theists and atheists over morals as this: a theist believes that our actions ultimately have some cosmic significance, whereas atheists tend to believe that an action is good or bad based upon the harm or benefit it brings. For example, a Christian believes that homosexual relations are an abomination in the eyes of god and that those who engage in such conduct as well as the society that condones it, are risking divine wrath. In contrast, most atheists do not consider homosexuality intrinsically wrong. Rather, there are certain degrees of risk to the act itself. As long as the participants in the act do not engage in reckless promiscuity and they are careful to use protection to reduce the risk of transmitting an infection, I fail to see why two consenting adults of the same gender giving each other sexual pleasure should be an issue for anybody. Nor does it seem remotely plausible to me that the act of Adam kissing Steve instead of Eve reverberates across the universe and causes some omniscient deity to engage in a furniture smashing tantrum in his celestial living room.
To be honest, I found it rather insulting to be told by some theists that my values were nothing more than my "personal preference." I felt it trivialized a value system I had developed through study and consideration as being akin to a consumer deciding they liked McDonalds over Burger King, Coke over Pepsi, or chocolate covered sprinkles over rainbow colored sprinkles. To dismiss someone's moral point of view as a mere preference, at least to me, is to attribute to it an almost whimsical flimsiness, as if an atheist who abhors the idea of child rape might one day decide, "Well, why not try it just once just to see what it is I am objecting too. Heck, I might even end up liking it!" And since I have no personal desire as a married, heterosexual man to have sexual relations with another man, I fail to see how my liberal views towards gays represents a "personal preference" for homosexuality.
Furthermore, my value system serves to act as a check on things that I would prefer to do. It would be great to lead an irresponsible life, drinking alcohol to excess, not showing up to work, maxing out my credit card, sleeping with whatever woman I desired. According to a theist, if I am a law unto myself, I might as well be doing these things. But I don't. Why? Because I am intelligent enough to recognize that there are consequences to these behaviors that can cause me irreparable harm. What would be more accurate to say is that we have hierarchical values. If one values having a house and amassing enough savings for retirement, for example, those values will serve as a check on one's baser desires to spend every penny on material things rather than socking money into a retirement account.
I would argue that my reasons for either engaging in or refraining from certain activities is not much different than a theist. We are both concerned with possible consequences. Where we part ways is over our differing beliefs as to what those consequences are. A Christian might desire to partake in certain activities but refrain from doing so because of a fear that he or she will commit a sin in the eyes of God and risk going to hell. I, on the other hand, will refrain from doing certain activities because I recognize they can have harmful activities in this life not only for myself, but possibly for others as well.
Another important thing to point out is that atheism itself is not a value system. Atheism is simply an absence of belief in a deity. It is not the source of one's values. Rather, by eliminating the possibility of a god as a source of morals, an atheist has to come up with other criteria for determining whether something is right or wrong. But as I wrote in the opening paragraph, an atheist does not simply make up these things from scratch. We are all shaped by a host of factors, such as culture, environment, and education. In other words, we draw upon whatever sources are available to us. Our values are not created in a vacuum.
I will concede that my value system is just that, mine. I would consider myself to be a humanist who believes that a society that upholds justice, fairness, and mutual respect and tolerance is, while not perfect, the best of all possible worlds. I also recognize that I do not have all the answers. Maybe some people cling to religion as their source of morality because they crave certainty in ther lives. If there is no god, then we really do have to figure things out for ourselves, stumbling and making mistakes along the way, and hopefully making refinements and improvements as we learn from experience. Perhaps it is easier to embrace the idea that a collection of books or texts such as the Bible or the Quran contains everything we need for determining what is right or wrong. But just because they purport to be the objective source of right and wrong does not make them so.