Pope Alexander VI was Pope from 1492 -1503. He was a Pope with no less than four illegitimate children. These four children were born of his long time mistress, Vannozza dei Cattanei, and were all born while he served as a Cardinal in the Church.
Pope Alexander’s main goal as Pope was to secure high places in the world for His children. His most famous child, Cesare Borgia, was originally to be a prince in the Church, so he was made bishop at the age of 15 and, after his father became Pope, he became a cardinal. He was, at that time, only eighteen. Cesare was a strong military leader, and with his father, the Pope's, assistance, he spent the majority of his father's pontificate fighting wars to extend the secular territory Papacy and power his and his fathers power.
Adultery, intrigue and murder were not unknown to the Papacy of Alexander VI. It is probable that he was involved in the death of a Cardinal now and then. He was suspected of playing a part in the poisoning death of one of them from time to time. When a Cardinal died he ceased their assets. So the death af a Cardinal was profitable for Alexander. He also made a good many Cardinals as well. The office, then, was for sale and Pope Alexander VI made a good income this way as well.
As Pope, Alexander took a new mistress, Giulia Farnese, who was the wife of another man. Alexander had a daughter by Guilia, while he was the Bishop of Rome. Guilia was referred to as “the Pope’s whore” and (more tongue-in-cheek) “the bride of Christ.”
When Alexander became Pope, Giovanni di Lorenzo dé Medici, the future Pope Leo X, said, "Now we are in the power of a wolf, the most rapacious perhaps that this has ever seen. And if we do not flee, he will inevitably devour us all.”
Pope Julius II, who gained the Papal throne in 1503, said, in a Papal Bull, “Our predecessor desiring to enrich his own kin, through no zeal for Justice, but by fraud and deceit sought for causes….”
After the death of Alexander, his many schemes collapsed and Cesare lost his land’s in Italy. Four years after his father’s death, he was killed at the siege of Viana, while fighting for his brother-in-law the King of Navarre. Cesare was thirty-one.
Pope Alexander is an example of the corruption and decadence that had become the Church at Rome. It is this Church that men, such as Erasmus, complained of in their just criticisms. Luther like Erasmus saw the corruption at Rome first hand.
I think such insight about the corruptions of that time, helps us to understand, just a little better, about the context of the then approaching storm that we call the Protestant Reformation.