God is not necessary for altruistic behavior to occur.
The kind of altruism we ought to encourage, and probably the only kind with staying power, is satisfying to those who practice it. Studies of rescuers show that they dont believe their behavior is extraordinary; they feel they must do what they do, because its just part of who they are. The same holds for more common, less newsworthy acts working in soup kitchens, taking pets to people in nursing homes, helping strangers find their way, being neighborly. People who act in these ways believe that they ought to help others, but they also want to help, because doing so affirms who they are and want to be and the kind of world they want to exist. As Prof. Neera Badhwar has argued, their identity is tied up with their values, thus tying self-interest and altruism together. The correlation between doing good and feeling good is not inevitable inevitability lands us again with that empty, unfalsifiable egoism but it is more than incidental.