When you professionalize and vocation-alize a spiritual calling, you can inadvertently limit (or misconstrue) who can both accept and fulfill that call. Why? Because spiritual calling is first and foremost tied to salvation and then expressed through personal obedience.
In other words, the "call" of disciple making, evangelism, and church planting is not reserved for those who have a seminary degree or carry the title Rev., Dr., Pastor, or missionary in their name.
The call of the Great Commission is for ALL who follow after Christ!