The aim of this study is to demonstrate that agent-based simulation is a scientific approach to studying the altruistic behaviours of a Bodhisattva, who is practising Buddhism to achieve Buddhahood. From the Buddhist perspective, the evolutionary model of Hammond and Axelrod (2006a) describes the operation of a community in the world. The study shows that we can simulate a Bodhisattva as a firm-and-pure-altruist (FPA) agent, who always performs both in-group and out-group altruistic behaviours, including the preaching of doctrine and the giving of material objects, and who always remains an FPA agent. Based on the model of Hammond and Axelrod (2006a), ordinary human beings are modelled as four-type agents who evolve according to their genetic potential to reproduce. Our results show that a Bodhisattva can create more pure altruists in the community by sharing doctrine and material objects. The results also show a beneficial situation because the average welfare of all four agents increases if we consider average fitness as a measure of welfare, according to Becker (1976).