Augustine’s thoughts on human salvation not only influenced early Protestant theology but also dominated the conceptualisation of the missio Dei from the perspective of the 1952 Willingen Conference. His doctrine of synergism arguably only manifested much later in the conception of the missio Dei, which anticipated human obedience or active participation in the mission to attain the goal of human salvation. The idea of synergism in this regard, or in the context of the missio Dei, is that while salvation remains an unmerited gift of grace through faith in Jesus Christ, God prescribes human cooperative involvement in its attainment. In this way people do not become unresponsive recipients of God’s grace, but active and willing participants in a mission of salvation. With this in mind, this article examined the available literature on the topic of synergism in order to provide further insights into the conceptualisation of the missio Dei. The account of Noah in Genesis 5:32–10:1 and the Great Commission in Matthew 28:16–20 were used to redefine the doctrine of synergism or its relevance in the context of the missio Dei.Contribution: This article recalled the doctrine of synergism in order to enrich the complex understanding of the missio Dei, essentially adding new knowledge in the field of missiology.