The contrary view, that immortality was man's natural condition, was condemned by Pius V and Gregory XIII
In the last century there were indeed some among the teachers of the Roman Church itself who held that the first man's immortality was not a gift of grace but his natural condition.
But the Roman popes Pius V and Gregory XIII condemned this view in a special bull in which they condemned many articles of certain recent theologians. Article 75 among them reads: "The immortality of the first man was not a gift of grace, but his natural condition." So Bellarmine himself testifies (On the Grace of the First Man).
Latin
XII. Fuerunt quidem nonnulli superiore saeculo, inter ipsos Doctores Ecclesiae Romanae, qui existimaverunt immortalitatem primi hominis non fuisse gratiae beneficium, sed naturalem ejus conditionem. Verum haec sententia fuit a Pontificibus Romanis Pio V. & Gregorio XIII. damnata in bulla singulari, in qua multos articulos recentiorum quorundam Theologorum damnaverunt. Inter quos articulos hic est 75. Immortalitas primi hominis non erat gratiae beneficium, sed naturalis ejus conditio. Ut testatur idem Bellarm. lib. de Grat. primi hominis.