He joined the ecclesiastical Padri of the Scuole Pie (Piarist order) in 1749 in Rome, and changed his name to Martino Natali.
He argued for the supremacy of the doctrine of St Augustine versus the modern dogma of Leclerc and Daillé.
He moved to teach theology in Pavia, and there met the Hapsburg emperor Joseph II.
He wished to limit the role of the pope in setting dogma, and urged that the church follow the beliefs of St Augustine on grace, predestination, and original sin.
He went so far as to argue that death prior to baptism withdrew an infant from God's protection, and led to his damnation.