I think the idea that there is an absolute moral code, and that the highest ideals humanity possesses all derive from God, leads religious believers to have very wrong ideas about atheists. "God is love" goes the saying. Or the corny billboard "Know God, know love. No God, no love". If might seem to follow that without God, we atheists are also without love, morality, selflessness, compassion, beauty and joy, and the other things that religious believers attribute to God. But this is not the case.
All those good things, those high ideals, are also held dear by atheists. We feel them strongly, we think they are of paramount importance. In fact I think these things are too important to be linked with a requirement to also believe in a whole lot of very strange supernatural claims. This to me that is the greatest flaw in Christianity. As I understand Christianity, the supernatural component - belief in Jesus as God, the miraculous event of the resurrection, the dualistic concept of a human soul whose well-being is dependent on acceptance of this mythology - these things are seen to be more important than the whole "love thy neighbour" bit. It's a flaw in Jesus' character that he established his cult on such nonsense, reducing him to the level of any other cult leader who claims to have a hotline to God and the power to perform miracles. There have been a few of them, these cult leaders, although in the modern world many of them seem to end up being accused of child sexual abuse, from Sai Baba all the way down to the appropriately named Wayne Bent.
There's science to explain altruism and even sacrifice. It's a mathematical, evolutionary truth that collaboration is a far far better strategy than individual action. This phenomenon exists biologically, even in species with nothing like consciousness or a nervous system, and it's a wonderful, amazing, inspiring thing. Peter Hitchens' claim that these things are "not natural" is simply absurd. The neurological structures which allow these traits to be transferred from our genes to our brains, interacting with learned behaviour which is inspired by other individuals who share a common genetic heritage, are also mysterious and inspiring. It will be exciting to see the science of the brain reveal the way these things work.