As to your Christian friend I have known atheists who have been unable to adhere to their own standards of morality. Everyone does it. We are but human. What religion offers is absolution and belonging. True enough these things can be found without religion, but it's often difficult to come by and for those who have already been exposed to it; it may seem impossible. Only one of many reasons that we will never be rid of religion.
I was not trying to imply that athiests did not do the same. The point being, we all do that, to an extent. Whether it is a big thing like breaking a law, or a small thing like taking the last slice of pizza.
The difference being that the religious are quick to claim the moral high ground on many issues attempting to use their religion as the backing of that claim, when in actuality, they themselves are using no more accurate an instrument than anyone else to judge morality. That is, of course, their own brain. Subject to predjudice, persuasion, snap judgement, and bais. Everyone comes to their own conclusions, but when you feel as though you hold a judgement based on some sublime insight, or revelation from a supreme moral authority there is no avenue for even the possibility that you might be wrong to find its way to you.
I hold my positions because i have a level of confidence that they are correct. That is not to say that i think they are correct absolutely. With the proper evidence i can and have changed my mind on many things because i realize that i came to my own conclusions, and they very well could be wrong. I used to have a much more close minded view on homosexuality. I was never a gay-basher, but i did think of it as a kind of mental disease, or handi-cap. I held those views because i was mis-informed.
The noisiest religious people hold that view, still, based on mis-information. including the mis-information that the bible is full of anti-gay rhetoric. Despite ample opportunity to change their minds based on cold facts and open, honest communication with real-life gays (rather than the marauding throng of rapists depicted here:
Genesis 19:4-5 describes what followed, which confirms its end (RSV):
But before they lay down, the men of the city, the men of
Sodom, both young and old, all the people to the last man, surrounded the house; and they called to Lot, "Where are the men who came to you tonight? Bring them out to us, that we may know them (KJV: know them, RSV: know them, NIV: can have sex with them , NJB: can have intercourse with them)."
They stubbornly hold onto their anti-gay attitudes because they have post-dated their predjudice to belong to God.
The same with the pathetic young earth creationism stance, intelligent design, and "god causes natural dissasters to punish moral issues.
Realizing that you came to your own conclusions allows you the lattitude to realize you may be wrong, or that others can be right. Here's a quote i enjoy.
"When i was young i was absolutely sure that i had all the right answers. When i grew older, i realized that i was right about all of those things, but i also realized that there are many OTHER ways to be right."
So, while i may like my beer because it tastes great. Someone else is not wrong to like it because it is less filling.