God wants us to be sincere. He makes this point very clear. He wants us to have a “sincere heart” (Ephesians 6:5), a “sincere mind” (2 Peter 3:1), a “sincere faith” (1 Timothy 1:5), a “sincere wisdom” (James 3:17), a “sincere devotion to Christ” (2 Corinthians 11:3), and a “sincere brotherly love” for other Christians (1 Peter 1:22).

So what does “sincere” mean? The English word has its origin in Latin, though etymologists have a few different theories as to the root words. Here is the one I find most convincing:

The English word sincere comes from two Latin words: sine (without) and cera (wax). In the ancient world, dishonest merchants would use wax to hide defects, such as cracks, in their pottery so that they could sell their merchandise at a higher price. More reputable merchants would hang a sign over their pottery — sine cera (without wax) — to inform customers that their merchandise was genuine. (Taking Hold of God, 69–70)

It is a powerful illustration and, I think, gets closest to what the biblical authors meant: Let your heart, mind, faith, wisdom, devotion, and love be genuine, the real thing, “without wax.”

Hard to Live Without Wax

We all know insincerity when we see it. Most of us really don’t like it when we see it in others. And we roundly condemn misleading marketing by mendacious merchants.

But most of us also find it hard to fully live “without wax” ourselves. I know this by observation and experience. I know it mainly because I know me. I am a clay jar (2 Corinthians 4:7) — and one that is quite flawed. And my sin-nature is a mendacious marketing merchant. It does not want you or anyone else to see my defects. It wants to hide the defects behind a deceptive wax and sell you a better version of me than is real.

Multiply me by about seven billion, and you get a real waxy mess of a world. The serpent gave Eve the “wax treatment” in the garden, and we’ve been “waxing” our wares for each other ever since.

The Gospel for Waxers

But Jesus came to transform selfish self-sellers like us into sincere lovers of others. He came to cleanse us dishonorable jars and transform us into honorable jars (2 Timothy 2:20–21). On the cross, as Jesus became sin for us (2 Corinthians 5:21), all wax was removed and our sin was revealed for what it really is: death and destruction. And then he took these sins away (1 John 3:5).

This truth means that Christians have nothing left to hide. We have no reason to wax ourselves to impress others. No, the one we want others to be impressed with is Jesus. And Jesus, in all his glorious genuineness, covers our sins in such a way that we don’t wax them over (Romans 4:7) and our weaknesses serve to show how gloriously powerful he is (2 Corinthians 12:9–10). Our insincere wax would simply cover up his glory.

Being a Christian means we can put the wax away! Isn’t that good news?

But our remaining, prideful sin-nature does not want to put the wax away. It wants to dress up the grace of Christ with the wax of self-exaltation and promotion. So we will be repeatedly tempted to rub a little wax on our Facebook post, or why we’re running late, or why the assignment didn’t get done, or why we lost our temper, or how old we are, or how much we know, or what’s really the condition of our heart. But let us not listen to our mendacious marketing merchant sin-nature.

Instead, let us seek to “do nothing from selfish ambition or conceit” (Philippians 2:3) and to love each other with a “sincere brotherly love” (1 Peter 1:22). Let us be real so that the reality of Jesus can be most clearly seen in us.