Why did Ferdinand and Isabella sponsor christopher Columbus?

Ferdinand and Isabella sponsored Christopher Columbus primarily to find a new trade route to Asia, aiming to access valuable spices and gold. They also sought to expand Spain's influence and prestige in the world, particularly as a counter to rival powers like Portugal. Additionally, they were motivated by a desire to spread Christianity and convert any new lands and peoples they encountered. Columbus’s promise of potential wealth and territorial expansion aligned with their goals, leading to their support of his expedition.