A native of Naples, he was the son of Giambattista Spinelli, marquis of Fuscaldo, prince of Sant'Arcangelo and duke of Caivano. His mother was Maria Imperiali. He was the grand-nephew of Cardinal Lorenzo Imperiali, cousin of Cardinal Cosimo Imperiali, and uncle of Cardinal Ferdinando Spinelli.[1]
At the age of thirteen, he was sent to Rome to live with his maternal uncle, Cardinal Giuseppe Renato Imperiali, while attending the seminary. In 1717, he was awarded a doctorate in civil and canon law from La Sapienza University.[1]
His clandestine attempt to introduce the Inquisition to Naples in 1746, resulted in a violent popular uprising, whereupon Charles III forced him to renounce his see and leave the capital. He did so with the greatest of reluctance, attempting first to remedy the situation from Rome, but finally resigned the Archbishopric in early 1754.[2]