The doctrine of pactum salutis has in the past sparked serious theological debate and has often been rejected because of its contradictions with Reformed orthodoxy. Among other early church fathers and theologians, the pactum salutis is found in the writings of Augustine of Hippo, Thomas Aquinas and Martin Luther. This doctrine is closely related to, or possibly overlaps with, the doctrine of predestination, as both involve the belief that God has already determined the object of his salvation. It has been criticised for, among other things, its denial or insufficiency of Trinitarian understanding and its pro-Subordinationist character. The refutation of this doctrine may be warranted, particularly when viewed in the light of contemporary missiology, particularly the Missio Dei perceptions that arose from the 1952 IMC conference in Willingen. As there is little or no research examining the rationality of the pactum salutis on the basis of or in the light of the Missio Dei, this article draws on the available missiological literature to refute its coherence, relevance and authenticity.Contribution: This article made a significant missiological contribution to the field of Christian theology, analysing the validity of pactum salutis against Reformed orthodoxy and consequently rejecting it as incompatible with the objectives of Missio Dei.