Even though research on perceiving a calling has been growing, our understanding of its double-edged sword effects and psychological mechanisms remain unclear, especially in terms of work engagement and workaholism. Based on the heavy working investment (HWI) and dualistic model of passion (DMP) theories, we established a dual-path structural model to examine the effects of callings on work engagement and workaholism through two types of passion: harmonious (HP) and obsessive (OP) passions. Our results showed that the association between perceiving a calling and work engagement was partially mediated by HP, while the association between perceiving a calling and workaholism was fully mediated by OP. This study contributes to the literature in that it reveals how perceiving a calling has different effects on work engagement and workaholism through the HWI theoretical lens, as well as the mediating roles of HP and OP, based on the DMP theory. Our findings can be practically applied in organizations and counseling.