In their new Intermediate Greek Grammar, David Mathewson and Elodie Ballantine Emig provide a lengthy quote from Martin Luther on the importance of the biblical languages:
For the devil smelled a rat, and perceived that if the languages were revived a hole would be knocked in his kingdom which he could not easily stop up again. Since he found he could not prevent their revival, he now aims to keep them on such slender rations that they will of themselves decline and pass away. . . Although the gospel came and still comes to us through the Holy Spirit alone, we cannot deny that it came through the medium of languages, was spread abroad by that means, and must be preserved by the same means. . . In proportion then as we value the gospel, let us zealously hold to the languages. . . And let us be sure of this: we will not long preserve the gospel without the languages . . . The Holy Spirit is no fool. He does not busy himself with inconsequential or useless matters. He regarded the languages as so useful and necessary to Christianity that he ofttimes brought them down with him from heaven. This alone should be a sufficient motive for us to pursue them with diligence and reverence and not to despise them . . . When our faith is . . . held up to ridicule, where does the fault lie? It lies in our ignorance of the languages; and there is no other way out than to learn the languages . . . Since it becomes Christians then to make good use of the Holy Scriptures as their one and only book and it is a sin and a shame not to know our own book or to understand the speech and words of our God, it is a still greater sin and loss that we do not study the languages, especially in these days when God is giving us men and books and every facility and inducement to this study, and desires his Bible to be an open book . . . The preacher or teacher can expound the Bible from beginning to end as he pleases, accurately or inaccurately, if there is no one there to judge whether he is doing it right or wrong. But in order to judge, one must have a knowledge of the languages; it cannot be done any other way.
In mission context, we severely stunt the growth of the church when we do not teach the languages. The goal of mission cannot be simply evangelism or even church planting. We must train church leaders and leaders of leaders to rightly handle the Word of truth. And, an important part of that training is the biblical languages.