Not being a Christian, I may be way off...but I have always felt that Christianity seems to focus so much on sin and everyone is a sinner and that we all need to ask for forgiveness. I really don't understand the focus on sin or immorality.
In the Buddhist philosophy, there are certain precepts or "morals" that should be followed similar to Christianity...Do not harm other living beings, speak truth, etc. but the focus is more on practicing moral behavior as opposed to assuming we are all going to sin and need forgiveness from a higher power. Morality comes from within...not laid down by societal beliefs.