It could be argued that 1233 is the year when people in general became suspicious about black cats. You can blame a gentleman whose name is Konrad von Marburg.
The 13th century was a time of huge superstition. Heretics were demonised by the church. There was the Inquisition. Heretics were those people who held beliefs different to orthodox religious doctrine and what was generally accepted at that time as the norm. The Inquisition was a period when the church wanted to root out, in a paranoid manner, heretics.
In 1233 Konrad (or Conrad) von Marburg, on the instructions of either the Pope of the Roman Catholic Church or the Archbishop, started an Inquisition in Mainz, now the capital of the state of Rhineland-Palatinate in Germany.
It is alleged that Conrad tortured people into making confessions, as a result of which it was reported that he had uncovered a satanic cult. This satanic cult worshipped the devil and a black cat. It is said that Conrad had forced innocent people to confess by threatening that they’d be burned at the stake if they refused to do so.
Because Conrad had unearthed these satanic rituals in which heretics worshipped a diabolical black cat, the Pope issued a papal bull (a charter) in which he urged others to seek out and destroy heretics. The papal bull was sent to King Henry and Siegfried III.
As a consequence, some historians say that the papal bull, called Vox in Rama (this is Latin for a “voice in Rama” – Rama was a city of ancient Israel) is the first official church document which condemned the black cat as an incarnation of the devil. In this document the cat is addressed as “Master”. The devil as embodied in human form is half man and half cat.
A gentleman called Engels (who I presume is an historian) claims that Vox in Rama was:
“A death warrant for the animal, which would be continued to be slaughtered without mercy until the early 19th century.”
As a result, it is said, that very few all-black cats survive in Western Europe. I think that last sentence is possibly incorrect because I think you will see quite a few black cats but perhaps in the 19th century there were very few of them unless someone on Continental Europe can tell me otherwise. But this papal declaration condemned hundreds of thousands of black domestic, stray and feral cats to a grisly end; quite shocking.
You will note, therefore, that the present-day superstition about the black cat, which is still strongly prevalent on the African continent and in many other parts of the world including in Western and developed countries, started with what we would now consider to be a perverse, bizarre, paranoid superstition that the black cat was the incarnation of Satan. Eight centuries later a lot of people still believe it. That’s humans for you. Don’t believe we are highly evolved and civilised.
Source information: Wikipedia.