So there's an answer that is not good in several respects:
It only offers a quote without context. The quote is biased (ultramontane, catholic historian in the 19th century) and very old (120 years). For details on the bias, see the German wikipedia page on the quoted historian.
The quote plays into antisemitic stereotypes of the type (blood libel, conspiracy (to kill all Christians), mutilation of crucifixes, by Jews etc.)
The quote is so obviously biased that it would not be acceptable to today's historians
What is quoted is a bad translation of an originally German text into English that is riddled with mistakes (Corpus Christi being translated as Good Friday)
Good answers should give context to any quote, even if the quote was not obviously biased and antisemitic
Good answers should, if possible, present the state of the art view of historical science on the question, not just one non-neutral perspective (and certainly not just one quote).
Normally I would downvote and comment on how the answer can be improved. This is not an option in the present case, because History:SE's current policy on comments causes my comments on this to be deleted immediately.
Alternative suggestions are to
write a better answer which would presumably be upvoted. This can only be done by someone who has enough insight to give a better answer that is not superficial. It does not allow people who are no experts on the matter of the question (early modern Spain) to raise the problems with this answer.
edit the answer and improve it. The answer currently has a flag recommending the latter. I do not think this is a good way to handle things, since it would change the nature of the answer substantially and in a way that the original author may not be happy with.
There was a bit of discussion about this in the chat resulting in the recommendation by multiple people that there should be a Meta question about this.
Edit (Feb 3 2020): in response to a comment about biasedness being subjective
I do not think it is true that biasedness is subjective. Opinions, perspectives, viewpoints may be subjective. But if a source selectively presents evidence for one viewpoint while ignoring others that are commonly accepted as valid perspectives among historians, then the source is biased. Note that following this approach, the biasedness may change over time as more information becomes available while an old historical text (that could not possibly have been aware of that information) cannot be updated. This does not invalidate the text as a historical source, it just means that it is not up to date any more and must be seen as biased by the common viewpoints of the time when it was created.
For instance in the context of the present example (the ultramontanist Ludwig von Pastor): In the 1800s, papal infallibility was a hotly discussed topic and the view that the pope could not possibly be wrong was not uncommon even among historians. Although non-Catholic historians surely held a different opinion, it would in itself not have seemed outrageously wrong. This was before we had modern psychology. In the light of the findings of modern psychology, claims of the infallibility of a human being would appear ridiculous. The Catholic Church has adapted to this (starting in 1870), and so has historical science.
Another example is scientific racism which was very much a thing at the time of Ludwig von Pastor. There were respectable scholars at the time who expressed antisemitic ideas in their writings. Today, this is not done any longer, old sources that do that are seen as biased, and quoting these without providing context is not acceptable.