Allowing the word apostle to signify a missionary, it does not seem to follow that calling an ordinary preacher, who is sent to publish the gospel among the heathen, by the latter name, is improper or “unscriptural.”
The word διακονειν, which is used of the office of a deacon, signifies to minister to the wants of others, or to serve. A deacon was a servant; but it does not follow that the application of the word servant to other persona as well as deacons is improper or unscriptural. A deacon was a servant of a particular kind; and such is the idea which the word conveys; but the term servant is more generic, and therefore is properly applied to persons who serve in other capacities as well as this. Every deacon was a servant, but every servant was not a deacon.
It should seem that the same may be said of αποστολος, the term used to express the office of an apostle. It signifies a messenger or missionary; but it does not follow that the application of either of these terms to other persons as well as apostles is improper or unscriptural. An apostle was a messenger, or missionary, of a particular kind; and such is the idea which the word conveys; but the terms messenger and missionary are more generic, and therefore are properly applied to any persons who are sent with a message to a distance. Every apostle was a messenger and a missionary, but every messenger and missionary was not an apostle. Epaphroditus was the αποστολος, or messenger to the Philippians to Paul (Phil. 2:25); and those who are called in our translation “the messengers of the churches” (2 Cor. 8:23) are denominated by the same name, αποστολοι. The word also that is used for the sending out of ordinary preachers of the gospel among the heathen, properly means to send on a mission; and is the same (with only the difference of the verb and the noun) as that which is rendered an apostle. “How shall they call on him in whom they have not believed? and how shall they believe in him of whom they have not heard? and how shall they hear without a preacher? and how shall they preach, except αποσταλωσι, they be sent?” Rom. 10:14, 15.
Upon the whole, I hope Eubulus will reconsider his censure of the translators, for naturalizing the term αποστολοι, when applied to those messengers immediately commissioned by Christ, by rendering it apostles, rather than translating it messengers or missionaries. The naturalization complained of resembles, in this instance at least, that of the common name by which we denominate the Holy Scriptures, calling them the Bible, from βιβλος, the book. To have translated this, and called it the book, would not have distinguished it from certain parts of it, which also bear that name, Matt. 1:1. But to call it the Bible suggests the very idea required; that is, the book by way of eminence, the book of books. So αποστολοι, if translated messengers, or missionaries, would not have distinguished the twelve disciples from other messengers, or missionaries; but, rendered apostles, it conveys the true idea; namely, that of messengers of an extraordinary kind, or messengers by way of eminence.
Excerpt from: “The Apostolic Office,” in Essays, Letters, etc. on Ecclesiastical Polity: An Inquire into the Right of Private Judgment in Matters of Religion.
Fuller, A. G. (1988). The Complete Works of Andrew Fuller: Expositions—Miscellaneous. (J. Belcher, Ed.) (Vol. 3, pp. 498–499). Harrisonburg, VA: Sprinkle Publications.