Economic reasons: Mexico was a rich source of natural resources, including gold, silver, and other valuable metals. Spain also wanted to control the trade routes between Mexico and the rest of the world.
Political reasons: Spain wanted to expand its empire and increase its power and prestige in the world. Controlling Mexico would give Spain a foothold in the Americas and allow it to challenge other European powers in the region.
Religious reasons: Spain was a Catholic country, and it wanted to convert the indigenous peoples of Mexico to Catholicism. Spain also wanted to prevent other Protestant European powers from gaining a foothold in Mexico and spreading their religions.
Demographic reasons: Spain wanted to increase its population and expand its territory. Mexico was a large and sparsely populated country, and Spain saw it as an opportunity to settle its own people and increase its power.
Ideological reasons: Spain believed that it had a right to rule over the indigenous peoples of Mexico. Spain viewed the indigenous peoples as inferior and believed that it had a duty to bring them civilization and Christianity.