Overview Historians generally recognize three motives for European exploration and colonization in the New World: God, gold, and glory.
Religious motivations can be traced all the way back to the Crusades, the series of religious wars between the 11th and 15th centuries during which European Christians sought to claim Jerusalem as an exclusively Christian space.
Europeans also searched for optimal trade routes to lucrative Asian markets and hoped to gain global recognition for their country.
The Crusades: increased religious intolerance and forceful religious conversion
The year 622 brought a new challenge to Christianity. Near Mecca, Saudi Arabia, a prophet named Muhammad claimed he received a revelation that became a cornerstone of the Islamic faith. The Koran, which contained the revelations received by Muhammad, identified Jesus Christ not as God but as a prophet. Islam spread throughout the Middle East and into Europe until 732.
Soon thereafter, European Christians began the Crusades, a campaign of violence against Muslims to dominate the Holy Lands—an area that extended from modern-day Turkey in the north along the Mediterranean coast to the Sinai Peninsula—under Islamic control, partially in response to sustained Muslim control in Europe. The city of Jerusalem is a holy site for Jews, Christians, and Muslims; evidence exists that the three religions lived there in harmony for centuries. But in 1095, European Christians decided not only to reclaim the holy city from Muslim rulers but also to conquer the entire surrounding area.
The Crusades provided the religious ideology for the Reconquista, which in turn inspired Atlantic colonization. The Reconquista, or reconquest, refers to the 800 years of violence and expulsion of Muslims from the Iberian Peninsula after the failed Crusades. The Crusades and the Reconquista cemented religious intolerance, and the Christians looked to colonization partly as a means of continuing religious conquests. Particularly in the strongly Catholic nations of Spain and Portugal, religious zeal motivated the rulers to convert Native Americans and sanctify Christian global dominance.

Violence in Jerusalem during the Crusades. Image credit: Wikimedia Commons
The lure of gold: finding new routes to trade Eastern goods
Despite the consequent religious polarization, the Crusades dramatically increased maritime trade between the East and West. As Crusaders experienced the feel of silk, the taste of spices, and the utility of porcelain, desire for these products created new markets for merchants.
Merchants’ ships brought Europeans valuable goods, traveling between the port cities of western Europe and the East from the 10th century on along routes collectively labeled the Silk Road. However, transporting goods along the Silk Road was costly, slow, and unprofitable. Muslim middlemen collected taxes as the goods changed hands. Robbers waited to ambush treasure-laden caravans.
As well as seeking a water passage to the wealthy cities of the East, sailors wanted to find a route to the exotic and wealthy Spice Islands in modern-day Indonesia, whose location was kept secret by Muslim rulers. The lure of profit pushed explorers to seek new trade routes to the Spice Islands and to eliminate Muslim middlemen.