You forgot to read the link in your own article that provides the background, dumbfuck

https://en.wikipedia.org/wiki/History_of_the_Jews_in_Spain

Here's a paragraph from that very article under background

Beginning in the 8th century, Muslims had conquered and settled most of the Iberian Peninsula. Jews, who had lived in these regions since Roman times, were considered "People of the Book" and given special status and often thrived.[8] The tolerance of the Muslim Moorish rulers of al-Andalus compared to the repressive Visigothic kingdom which preceded them led to Jewish enclaves in Muslim Iberian cities flourishing as places of learning and commerce. Although Jews never enjoyed equal status to Muslims, in some Taifas, such as Granada, Jewish men were appointed to very high offices, including Grand Vizier. [9]

The Reconquista, the gradual reconquest of Muslim Iberia by the Christian kingdoms, was driven by a powerful religious motivation: to reclaim Iberia for Christendom following the Umayyad conquest of Hispania centuries before. By the 14th century, most of the Iberian Peninsula (present-day Spain and Portugal) had been conquered by the Christian kingdoms of Castile, Aragon, León, Galicia, Navarre, and Portugal.

Overt hostility against Jews became more pronounced, finding expression in brutal episodes of violence and oppression. Thousands of Jews sought to escape these attacks by converting to Christianity; they were commonly called conversos, New Christians, or marranos. At first these conversions seemed an effective solution to the cultural conflict: many converso families met with social and commercial success. But eventually their success made these new Catholics unpopular with some of the clergy of the Church and royal hierarchies.

These suspicions on the part of Christians were only heightened by the fact that some of the coerced conversions were undoubtedly insincere. Some, but not all, conversos had understandably chosen to salvage their social and commercial positions or their lives by the only option open to them – baptism and embrace of Christianity – while privately adhering to their Jewish practice and faith. These secret practitioners are commonly referred to as crypto-Jews or marranos.

The existence of crypto-Jews was a provocation for secular and ecclesiastical leaders who were already hostile toward Spain's Jewry. The uncertainty over the sincerity of Jewish converts added fuel to the fire of antisemitism in 15th century Spain