Why did Pope Nicholas V turn bad?

Answer 1

Pope Nicholas V did not "turn bad", he was a wonderful pope and is particularly remembered for the many good things he accomplished, especially as regards those who love letters (books, writing, etc.). The Catholic Encyclopedia ends its article about him with these words: A scholar rather than a man of action, he underrated difficulties, and was impatient when he was not instantly understood and obeyed. At the same time he was obliging and cheerful, and readily granted audience to his subjects. He was a man of sincere piety, simple and temperate in his habits, He was entirely free from the bane of nepotism, and exercised great care in the choice of cardinals. We may truly say that the lofty aims, the scholarly and artistic tastes, and the noble generosity of Nicholas form one of the brightest pages in the history of the popes.

For a discussion of various things held against him today by modern people without an indepth knowledge of the times, please see the discussion page added by PiusX.

See the Catholic Encyclopedia article about him below.
Pope Nicholas V:http://www.newadvent.org/cathen/11058a.htm

Moreover, Pope Nicholas V should not be confused with Antipope Nicholas V.

Answer 2

Pope Nicholas V, pope from 1447-1455, should not be confused with Antipope Nicholas V. Pope Nicholas V is considered one of the better popes of history, having encouraged learning and Humanism. He would no doubt have thought of himself as an honourable man, as he was by the standards of many past popes, but far from perfect by the standards we set today.

One blot on his character is that he issued the papal bull, Dum Diversas, authorising the Portuguese to capture and permanently enslave 'Saracens and pagans' of West Africa, helping create the conditions for the American slave trade. He forbade Christians to employ Jewish physicians, although at this point in history, Jewish doctors were in the lead in medicine. No doubt he saw both of these decisions not as 'bad', but as helping the Church and its faithful servants.

He made Valerio Galeotto a papal notary only a few days after his birth was legitimised, although he had still been under age, an action that Tanya M. Reimer (Thesis, San Diego State University) calls an excellent example of the simony which was rampant during the Italian Renaissance. No doubt honest by the standards of his day, he probably would not have given a thought to granting small favours in return for largesse.

Nicholas V was sufficiently unpopular that a conspiracy to kill him was uncovered just before it was to be enacted.