Whether Christians needed to launch the Reconquista is, of course a matter of perspective. What we can say is why it was launched. Really the Reconquista was a long struggle between the so-called Moors of North Africa and a variety of Christian monarchs from a number of Iberian kingdoms. This process really began with the conquest of much of Iberia by the Moors in the eighth century A.C.E. and did not end until 1492, a propitious year for other reasons as well (Christopher Columbus made his "discovery" that year.)
In short, the Reconquista had were several purposes. These were:
- To "reclaim" lands conquered by the Moors for Christianity. The Spanish forced conquered Muslim people to convert to Christianity. This applied to Jewish Iberians as well, who had moved to the region due to the Moors' reputation for religious tolerance.
- To take land for private use. Spanish Christian nobles in particular eyed Muslim lands for conquest, and sacked and claimed them as their own when they took them by force. This process, by the way, would repeat itself in the New World in the sixteenth century.
- To unify the Iberian peninsula. This became a goal only late in the reconquista, and was achieved by final defeat of the Moors following union of Castile and Aragon by the marriage of Ferdinand and Isabella shortly before 1492.