God is a lunatic
God hates homosexuals (Leviticus 20:13)1 and women (1 Corinthians 14:34). God condones polygamy (Samuel 12:8) and slavery (Exodus 21:20).
God is a mass murderer. With the exception of Noah and his family, God drowns everyone and everything on earth in a worldwide flood (including the dinosaurs apparently). He orders Abraham to murder Isaac. He commands Moses to slay the Midianites including the women and children, except the virgins, those he tells Moses to save for himself. Thanks God! The death toll grows ever larger and more violent with the turning of each blood-soaked page.
But… that all changed with Jesus didn’t it?! There is a “new covenant with Christ” which is established the moment Jesus sacrifices himself.
Did the covenant with God (and the Old Testament laws) change with Jesus’ sacrifice? Does it matter either way?
Jesus says in Matthew 5:17 that “he came to fulfill the law, not destroy it.” This seems to suggest that Jesus is not in fact abolishing the prejudicial Old Testament law.
Furthermore Jesus would have been very well versed in Old Testament scripture. He would have read and understood all of the misogynistic and genocidal passages earmarked above. Therefore, Jesus is giving tacit approval of all of the monstrosities committed by God in the Old Testament and of all of the abhorrent Old Testament laws (whether or not they remain in effect post-Jesus).
Additionally, Jesus was not the “great moral teacher” that many think he was. This article from atheism.about.com argues that Jesus was hypocritical (Matthew 5:22 and Matthew 23:17) and praise-hungry (Matthew 22:37-38).
Vicarious redemption via blood sacrifice, a.k.a. scapegoating, is barbaric
Jesus (allegedly) allowed himself to be tortured and executed to pay for the sins of humanity, this is the central tenet of Christianity and it is cruel and barbaric.
The fact that this sacrifice is even necessary is based upon another barbaric doctrine, original sin. The notion that all human beings are born sinners because Adam and Eve merely disobeyed God, is both ludicrous and evil.
Here is Christopher Hitchens on vicarious redemption:
The golden rule is an inherent part of being human and realizing what it is to be human
I experience pain and pleasure. I have very good evidence that almost every other human being I encounter is capable of having painful and pleasurable experiences much like my own. Pleasure is preferable to pain. Therefore I am compelled whenever possible to do no harm to my fellow human beings.
Because we all intrinsically know what it is to be human, and because we all want to be treated with respect and compassion, the “golden rule” is essentially a given. It’s not exactly inborn, but it’s so obvious that cultures the world over teach it to their children when they’re very young. I imagine some people come to realize and obey the golden rule on their own, without being taught.
This is the reason that most religious people DON’T obey the bible in its entirety.
In a civilized society, morality based on ethical principles supersedes (and historically precedes) religious morality. Christianity has long since jettisoned the misogynistic and slavery-condoning principles of its youth.
Ethics-based morality prevents Christians from enforcing the terrible laws described in Leviticus. In fact, religious and secular people alike agree that Christians who attempt to live by Levitical law are monsters, ex: The Westboro Baptist church.
Divine command theory is paradoxical
The “Euthyphro dilemma” proposed by Plato (originally by Socrates) can be stated as follows, “Is an act good because it is good, or is it good because it is commanded by God?”
If divine command is what makes an act pious, then if God were to command us to rape and murder acts of rape and murder would be pious.
If an act is good because it is inherently good, then God is not necessary to determine the morality of an action; furthermore if God is constrained by an external morality, then he is not omnipotent.
Morality is Common in Animals
If you have about 15 minutes, this is an excellent video from TED which makes the case for complex animal morality. Frans de Waal, Do Animals Have Morals?