So, when I was first exploring life without god, I realized that it wasn't just god I was giving up. I was also giving up a religion and all the trappings that went along with it. I was suddenly on my own when it came to determining right and wrong, good and bad, etc. I was forced to come up with my own morality. At the time, this scared me. I've since realized that this terrifies believers.
Many of the good believers out there will tell you that without god, there is no morality. Anything goes. Once you start down that "slippery slope" (they LOVE talking about slippery slopes!), the next thing you know, you're murdering for fun and having sex with animals. [Side note: Have you noticed that all the christians' slippery slopes end in animal sex? "If we allow gay marriage, next thing you know people will want to marry their poodles, and pretty soon all our pets will all have bloody anuses!" If you're wondering why, it's because that's exactly what a lot of them would do if they didn't have Jesus.]
As it turns out, developing a personal morality isn't difficult. It ends up mostly just being about treating others respectfully and not doing anything that would unduly hurt anyone else. Day to day philosophical morality is actually a lot simpler than all the nutty rules the believers have. There's no need, for example, to worry about whether or not it's sinful to eat shellfish anymore (not that I ever met a christian who did worry about that, despite the bible's proclamation that it's sinful). All you've got to do is balance your desires with thoughts of harms you may do to others, and go from there. Easy, really.
The problem with getting your morality from a source other than deep thought and inward reflection (like, say, a two thousand year old book) is that you end up with no personal connection to the rules you subscribe to. You know you're not supposed to do something, and you believe that you'll be punished if you do it, so you stay clear. It's a child's view of wrong and right.
That's all well and good, but it means that if you're confronted with an alternative point of view, you can't effectively argue your position. You're stuck saying "the bible says so, and that's all I need to know" regardless of how patently stupid or untenable your position is. Or- and this is worse- you wait for some "leader" like Pat Roberston or the pope or Limbaugh or somebody to come up with an argument for you. Now, you have no personal connection to your position or the outrageously fallacious argument you're using to support it.
Belief left unscrutinized is meaningless.
Faith makes people stupid.