Back then, it was mostly because of the bolt that was shot from them and the damage it did. The church goers (heavilly religous) thought it was terrible what a crossbow could do.
I've done a lot of reading into the history of crossbows. From what I've learned... First part of your comment is true. Second part, about the church goers... not entirely.
It was because the crossbow putin the hands of the common peasant soldier a weapon that could penetrate the armor worn by the nobles. Peasants couldn't contribute much gold to the Catholic Church's coffers because they didn't have much gold, if any. The noble class was where the money came from. It was fine and dandy for the nobility to slaughter unarmored, practically defenseless - and penniless -peasants in battle, but we couldn't have peasants armed with weapons capable ofkilling off the Church's most important contributors and cutting it's income, now could we?
That's why Pope Innocent II and the2nd Lateran Council banned the use of the crossbow by Christians against Christians in 1139, though disguised as being on Holy grounds.
Another bit of the puzzle is due in part to public sentiment overthe death of King RichardI (Richard the Lionheart) who was killed by a crossbow bolt, to be replaced by his hated brother, Prince John.
Further, the English Longbow became the country's national weapon after the overwhelming victories over the French at Crecy and Agincourt. A long line of England's kings, in order to maintain England's proficiency with the longbow,banned the use of crossbows among the common folk and mandated compulsory practice with the longbow to the exclusion of all other ranged weapons and all other sports. Anyone caught with a crossbow was automatically acriminal and probably a poacher of deer in the King's forest.Although... Those same kings that forbade the use of crossbows by their own people had absolutely no qualms about hiring crossbow mercenaries from the mainland to fight for them.
That is the condensed story abouthow the crossbow got theblack reputationof being 'the weapon of criminals, poachers,mercenaries and assassins.'
The crossbowbans came to us in the U.S. because many of our laws and much of our legal system is based on English Common Law. And here we are, hundreds of years after the true facts have faded into obscurehistory, dealing with midieval rules and mindsets.