"Missionary zeal" refers to a strong passion and enthusiasm that a person or group has for spreading their beliefs or trying to convert others to a specific cause, often driven by a desire to help or make a positive impact. Full definition
He is eloquent on the subject of «the unique religious system present within each congregation,» and speaks with missionary zeal of «the bulky body of symbols and stories and values and beliefs and histories contained therein which lie just beyond the grasp of any of the quantitative tools at our disposal.» (religion-online.org)
Something approaching missionary zeal for the rural ministry has developed in this century as an increasing number of young men have decided to devote themselves to it. (religion-online.org)
Of course Pope Francis is right: the Church must be renewed in missionary zeal and she must reach out anew to the whole of humanity. (faith.org.uk)