This is what is known as the Great Commission. In the original language, these words are a command. That is why we call this the Great Commission and not the Great Suggestion. And I believe that to fail to do this actually could be a sin.
In some Christian traditions, the church elder is an appointed person who usually serves a local church or churches and who has been ordained to a ministry of word, sacrament, and order, fulfilling the preaching and pastoral duties.