growstuff the persecution of Jesus Christ was the start, but like anything, once something starts, particularly over 2,000 years ago, the cause is soon forgotten.
I think there is an instinct for society to want scapegoats, someone to blame for anything that goes wrong and to build society cohesion on blaming hating one group for societial ills.
Anti-semitism did abate, although never go away, when we had an influx of immigrants, who were easily identifiable because their skin was a different colour, and they became our scapegoats for crime anti-social behaviour, and all the rest.
But a hatred of those who have money or who deal with money is always with us. Look at how, even today, we hate banks, rail against bankers, impute the worst of motives to them, love news stories that reveal their domestic problems or bad behaviour, both the companies and the individuals that run them.
This connection between money, banking and Jews, is what makes anti-semitism such an ingrained and institutionalised problem with left-wingers of all persuasions.
Incidentally, born and brought up a catholic, even in the 1970s, catholics too were distrusted for their internationalism and because they looked to a spiritual leader who was not British.
I come from an army family, my grandfather, great uncles, father and brothers, catholics everyone, were all professional soldiers, several died and won gallantry awards fighting in the British army, yet I heard and read people make arguments that catholics should not be in the army, nor in any post that involved the countries governance because they owed allegiance to an Italian pope and that if he told them to stop fighting, for example, or follow a policy that was to Britain's disadvantage, they would, because their first allegiance was to the pope. I think if a member of the royal family marries a catholic, they are still automatically excluded from the line of accession. This happened to the Duke of Kent's son and also his brother when they married catholic women.
However this is gone and forgotten now - but of course catholics were not seen as being bankers or financiers.