In this article Alypius' road to Christianity is being scrutinized. This first part examines Alypius' conversion moment - recounted in Conf. VIII.xii(30)- in great detail. The central question here is : to what exactly did Alypius believe he converted in that fateful garden of Milan together with his dear friend Augustine? A close analysis of his conversion passage suggests that he decided there and then to become an ascetic christianus as well, but that this not automatically involved baptism, while Augustine's mind was already set on baptism at his conversion. The story of Victorinus' conversion may have played an important role in this difference, since only Augustine heard this story from Simplicianus. Other indications, such as his strong inner virtue and his classical outlook on life, can explain why initially Alypius preferred a less committed place within the catholica ecclesia.