Human beings possess empathy and a desire to help the less fortunate entirely apart from religion or its rewards. From a purely utilitarian standpoint, one could argue that the reward of altruistic behavior within a social hierarchy is the strengthening of social bonds and likelihood of reciprocity, and this behavior has been seen in other primate species besides humans, suggesting it has an evolutionary benefit. Unfortunately, thousands of years of religious indoctrination has led many people to believe that humans are essentially amoral sociopaths without religion. But religion doesn't generate morality, ethics or virtue so much as codify them into a culturally specific framework.

That said, Jesus commanded his followers to practice charity often and directly linked doing so with gaining rewards in heaven.