In this study I aim at providing a new assessment of Ockham’s proof for God’s existence. After reconstructing Ockham’s views of the relationship between philosophy and theology (§1), I move to examining Ockham’s criticism to some traditional arguments (§2), before to scrutinizing closely Ockham’s argument. My main conclusion is that Ockham did not want to elaborate a new proof but to qualify the proof stemming from efficient causality, which he considers the only available way of demonstrating God’s existence.