How could the religious zeal to spread Christianity have led to or caused European exploration

Preaching the gospel has been a common argument to justify investment from European Kings and Catholic Chruch to explore new lands.

Explanation:

Since the beginning of Catholic Church as a institution, it has always been interested on spreading its religion not only in Europe but also in foreign lands. It has been very common to promote different misionary travels around the world becasue that is the way they can convert people from other lands and increase its influence beyond the European continent, which sometimes has overlapped with the personal motives of Europeans explorers, kings and coquerors.

The europeans wanted to teach christianity to others