Consider, for instance, organized religion. As an institution, it is notoriously corrupt. From the very beginning, Christianity, Islam, and Judaism have struggled with corruption from within -- the religions' very holy books say so.
But things take on a very different flavor if you evaluate religions as "influences" -- comparing them to the surrounding milieu, and asking what direction they pulled.
If you compare the Inquisition to the religious liberalism of today, it looks horrible. But what was the context?
Trial by Ordeal was a major determinant of "justice" from ancient through medieval times.
Hammurabi wrote, "If any one bring an accusation against a man," Hammurabi wrote, "let the accused go to the river and leap in. If he sink in the river, his accuser shall take possession of his house. But if [the accused] escape unhurt, then he who had brought the accusation shall be put to death."
This practice was still common in Western Europe through the Early Middle Ages. The Old-English, Proto-Germanic, and Dutch words "ordel, urteil, and oordeel" take their definition explicitly from the practice, meaning "Judgment, verdict."
Indeed, the term ordeal itself still bears this form of legal process as its primary definition
Who forbade bishops to participate in it? Pope Innocent III. He introduced compurgation instead (the accused vows his innocent, and his innocense is vouched for by a required number of other people). Justice? Not really. But much better than what came before it. And who brought that change about? The Christian author of the Albigensian Crusade, of all people.
Also consider what was happening prior to the crusades to heretics. Mobs in the streets, hunting down heretics at whim. The Albigensians themselves killing a papal envoy sent in peace.
The Inquisition, as horrible as it was, was a step forward from the "justice" of the rest of the world at the time.
Slavery, also. Slavery is explicitly permitted in both the Old and New Testaments. But not unqualified slavery. While the Greek and Roman pagans were permitted by law to kill, rape, torture, and abuse at will, the Jews and Christians were not. Jews were enjoined in Exodus 21:1-6 as follows:
“When you buy a Hebrew slave, six years shall he serve; and in the seventh shall he go out free, for nothing. If he came in by himself, he shall go out by himself: if he were married, then his wife shall go out with him. If his master has given him a wife, and she has borne him sons or daughters, the wife and the children shall be her master's, and he shall go out by himself. And if the slave shall plainly say, I love my master, my wife, and my children; I will not go out free: then his master shall bring him unto God, and he shall bring him to the door or unto the door-post, and his master shall bore his ear through with an awl, and he shall be his slave forever.”
Also, Exodus 21:16: "Whoever steals a man and sells him, and anyone found in possession of him, shall be put to death."
The ideas that slavery was temporary (only 6 years, or voluntarily after that), and that kidnapping and stealing slaves was wrong, were revolutionary. Even in the 19th century, the slaves brought to America were initially captured by Africans who raided rival villages, capturing and selling whoever they could to the whites.
And there was no "6 year rule" in the American slave trade.
In other words, the slavery of the 19th Century still violated the rules set in Exodus 3-4 thousand years prior.
And it was a heck of a lot better than the slavery going on in the Greco-Roman world.
So if you look at organized Christianity as put into practice, you often see many abuses and immoral behaviors. But if you look at organized Christianity in its cultural context, things start to look significantly different.
The key, it seems to me, is to evaluate innovators based on what differentiated them from their cultural context, and not what they retained. Thus if I am a racist in a town of racists, but I challenge the idea of slavery, then I should be evaluated for the innovation or influence I sought, rather than the culture baggage I retained.
Consider Constantine, for example. Certainly a brutal, superstitutious emperor in a time of brutal, superstitutious emperors. But he was unprecedented in his banning of gladitorial fights, and his introduction of religious tolerance.
Or consider the author of "Uncle Tom's Cabin." Certainly it promulgated a number of stereotypes of blacks held by many at the time; but it was revolutionary in its opposition to slavery. She should be evaluated not by the cultural baggage she retained, but by the new ideas she brought to the table.
Or consider Martin Luther. Judgmental, dogmatic and and racist, certainly. But he also lived in a judgmental, dogmatic, and racist time. How did he differ from his cultural context? He fought indulgences, fought for individual thought with respect to religious truth, fought against superstitious worship of relics ... insofar as he differed from his cultural context, he was a pretty good guy.
Does that mean we don't criticize the old culture? Of course not. Racism, slavery, and inquisitions are all bad things. But I think when we evaluate the people involved, we need to distinguish their radical flashes of insight (which are to their credit) from their cultural baggage (which, it seems to me, is less their fault than their heritage).
Thus a person who keeps 9 cultural prejudices and overcomes 1 is a cultural innovator. We can't blame people for being unable to overthrow every bias of their upbringing. We can only credit or blame them for the things (good or bad) that they bring to the table -- how they differentiated themselves from their environment.