Preachers need to be well trained and able to speak clearly. They need to be able to rightly divide and apply the word of truth. They need to be able to study. There will always be the occasional Charles Spurgeon or Martyn Lloyd-Jones, who, with little or no formal training were yet outstanding preachers, but they are the exceptions, not the rule, and even they might have been better had they been taught the biblical languages. There is a reason why the Reformers required rigorous study as a prerequisite for pastoral ministry: most aspiring ministers urgently need that if they are to preach the word with any degree of competence.
—Trueman, Carl R. Grace Alone—Salvation as a Gift of God: What the Reformers Taught…and Why It Still Matters (The Five Solas Series) (p. 192). Zondervan. Kindle Edition.