I, personally, do not think that morality can be objective, because your view of morality can often depend on your worldview. Some people believe in absolute morality (ie, morality is unchanging, set-in-stone, permanent) and this is very popular with the religious. Others believe in moral relativism, which says that morals are flexible and change over time with how we understand the world. That in itself seems enough to me that morality can't be objective, because we choose how to view morality from a personal standpoint.