From William MacDonald's devotional book, "One Day at a Time," available at www.thebereancall.org.
"For the Word of God is living and active and sharper than any two-edged sword" (Hebrews:4:12a, NASB).
A Christian university student was witnessing to another student who was from a liberal seminary. When the believer quoted a verse, the seminarian said, "I don't believe the Bible." The Christian quoted another verse, only to be met with "I told you I don't believe the Bible." The third time the Christian quoted a verse the seminarian became agitated and exploded, "Don't quote the Bible to me. I've already told you I don't believe it." By then the believer felt completely frustrated and defeated. He figured that he was a total failure as a soul winner.
It so happened that Dr. H. A. Ironside was a guest at his home that night. At the supper table, the Christian student shared his disappointing experience about the seminarian. Then he asked Dr. Ironside, "When you are trying to witness to someone and he says to you, 'I don't believe the Bible,' what do you do?” Dr. Ironside replied with a happy smile, "I just quote more of it."
That is excellent advice for any would-be soul winners. When people say they don't believe the Bible, just quote more of it. The Word of God is living and powerful. It has an effect on people even when they don't believe it.
Suppose two men are dueling. One says to the other, "I don't believe your sword is real steel." What happens? Does the second man lay down his sword and admit defeat? Or does he give a scientific discourse on the carbon content and malleablility of the metal? Ridiculous! He gives his opponent a good sharp jab and lets him feel how real the sword is. So it is with the Bible. The Word of God is the sword of the Spirit. It needs to be used more than it needs to be defended. It is well able to defend itself.
I do not deny that there is a place for proofs of the inspiration of the Scriptures. Such proofs serve a valuable purpose in confirming the faith of those who are already saved. In a few cases, they help people come to saving faith. But generally speaking, people aren't convinced by human reasoning or arguments. "A man convinced against his will is of the same opinion still." Men need to be confronted with the powerful Word of God. A single verse of Scripture is worth a thousand arguments.
This highlights the importance of Scripture memorization. If I haven't committed verses to memory, the Spirit will not be able to bring them forth at the appropriate time. But the main point is that God has not promised to honor my words, but He has promised to honor His own. So in dealing with the unsaved, I must use the sword of the Spirit generously and watch it produce conviction and conversion by a miracle of grace.