The phrase “iron sharpens iron” is found in Proverbs 27:17: “As iron sharpens iron, so one man sharpens another.” There is mutual benefit in the rubbing of two iron blades together; the edges become sharper, making the knives more efficient in their task to cut and slice. Likewise the Word of God is a ‘double-edged sword’ (Hebrews 4:12), and it is with this that we are to sharpen one another—in times of meeting, fellowship, or any other interaction.
The Proverb also indicates the need for constant fellowship with one another. Man was not made to be alone, for did not the Lord God say this, even before the Fall (Genesis 2:18)? How much more, then, after the Fall of Man, do we need to come together with our brothers and sisters in Christ for seasons of fellowship and prayer. Clearly this was recognized by the saints of the early church (Acts 2:42–47) who “devoted themselves” to the teaching, fellowship, communion, and prayer, all corporate activities that provided opportunities for sharpening one another. The result was that they were “filled with awe” and when they met together, they praised God for the favor they found with one another.
There are two points to make about the above proverb. First, the meeting of two together in the Lord’s name will always guarantee blessing. It is a means of grace that the Lord Himself promised—where two or more are gathered in His name, there He is among them (Matthew 18:20). Also, we see a similar meaning in Malachi for those who feared the Lord talked with each other, and the Lord listened and heard (Malachi 3:16). When we sharpen one another in real Christian fellowship, the Lord bends an ear from heaven and is pleased. Not one word about Him which brings Him glory escapes His notice.
The fragrances of divine ‘unity’ are best sensed in the relationship of David and Jonathan, son of Saul. When David was being hotly pursued by Saul, Jonathan sought David out “to help him find strength in God” (1 Samuel 23:16), which leads us onto our second point. Iron sharpening iron is an opportunity to fulfill the Law of Christ. The apostle Paul says that we are to carry and share the issues and burdens that we face daily, to lament over personal sin, advise on how best to repent of it, and rejoice over the conquest of it. This is the same “royal law” mentioned in James 2:8, where we are exhorted to love one another.
Returning to the analogy, if a knife is blunt, it still continues to be a knife, although it is less effective, less useful in the Lord’s service. Let us therefore be encouraged to spend more time together, exhorting, encouraging, praying, admonishing, sharing God’s Word, praying over God’s Word and the needs of our local church, that we become sharper, more cutting in the ministry that the Lord has assigned to each of us. Too often what passes as fellowship in the modern church is centered on food and fun, not on sharpening one another with the Word of God. In far too many instances, the only knives being sharpened are the ones used at potlucks.
Finally, a knife that has been sharpened will also shine more because all the dullness has been rubbed off its surface. Likewise, we will shine better for our Lord if we do the things mentioned above consistently, all of which will unite us in harmony. “How good and pleasant it is when brothers live together in unity” (Psalm 133:1). Therefore, as the author to the Hebrews says, “And let us consider how we may spur one another on towards love and good deeds. Let us not give up meeting together, as some are in the habit of doing, but let us encourage one another—and all the more as you see the Day approaching” (Hebrews 10:24–25).
 Got Questions Ministries. (2010). Got Questions? Bible Questions Answered. Bellingham, WA: Logos Bible Software.