But where is the authority for ordinary or newer disciples to go about “preaching the word”? Think again about the Great Commission (Matthew 28:18-20). Jesus receives “all authority” and directs His disciples,
Make disciples of all nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all that I have commanded you. And behold, I am with you always, to the end of the age” (Matthew 28:18-20).
When those first disciples teach obedience to all Christ commanded them, that includes the most recent command, “Make disciples!” In obedience to this command, the next disciples go and make disciples, baptizing them, and teaching them to obey “all” Christ’s commands, which includes “make disciples.” In obedience, the next set of disciples do the same, as do the next, and the next, generation after generation, until the end of the age. The authority for every disciple to make disciples comes from the Lord Himself. He built it into the self-replicating nature of the Great Commission.