This one comes to us from our friend Michael Belote of Reboot Christianity (who recently published a terrific write-up of Game of Thrones, btw):

Earlier this week, I found myself groggily trying to explain the concepts of engineering specifications and process controls to a Danish colleague via conference call at 5 am. About halfway through, it occurred to me how well this could serve as an extended metaphor for the Gospel. Bear with me.

Let’s pretend that you are an engineer helping to design a bridge. Your part of the project is to specify and oversee the incoming quality of the structural bolts. In order to do so, you must first create the engineering specification: the specification can be thought of us as the “design boundaries” within which the product must remain in order to perform as expected. So the material quality must be within certain parameters, the bolt length and width must be within certain parameters, the chamfer must be appropriate, etc. After some calculations, you are able to set up the specifications. For example, one such specification might be that the bolt head width (“N”) must be 10.55 + 20 mm (i.e., 10.35-10.75mm).


This specification is sent to the bolt factory, who sets up their line to determine if they can meet the tolerances.

We manufacturing engineers are well aware that, given enough samples, anything we make will have a quality which falls into a normal distribution (Bell curve), as shown below. On this distribution, we add two lines: an LSL (“lower spec limit”: 10.35mm, in our example) and a USL (“upper spec limit”: 10.75mm, in our example) to serve as boundaries of what is “appropriate”. If you go outside of the boundaries, the product must be either scrapped completely or reworked (forced to come back within specification).

For each of the many aspects of the bolt, this analysis must be done—what is good and and what is bad? Call it the Goldilocks zone: we want a bolt which is neither too small nor too large; which is neither too stiff nor too pliable; which is neither too thin or too thick. We want a bolt which is just right for the application’s design.

What occurred to me when I was on the phone is how fervently we humans desire to be able to approach righteousness in the same way.

We all know that we are not perfect: our righteousness on any given day is going to be a Bell curve, to say the least. We may think of ourselves as “honest”, but we know that there’s some variance in that regard: some days we are more honest and others we are less.

What you and I want to know is this: at what point are we no longer “right” with God? We want to know His upper and lower specification limits, if you will. We want to say, “Okay God, I know I’m not perfect…but am I still ‘within specification’? Am I ‘good enough’ to avoid being reworked or scrapped?”

I would argue that the majority of religion can be viewed from this vantage point. We are told what behaviors are acceptable, and in what ways, so that we know whether we are living between the specification boundaries. If we step out of the boundary, religion tells us what is next: either rework (sacrifices, penance, etc.) if you stepped out just a little, or scrap (excommunication/damnation) if you stepped out too far.

And the fact is that we want our religion(s) to be this way. We want to know what we must do to stay between the lines. Like the rich young man (Mt 19:16), we ask either explicitly or implicitly, “what good thing(s) must I do to gain eternal life?” Because if we have a specific checklist to follow, then we feel we are in control. We do not have to give up control to Someone else, and we remain our own gods, with our destiny in our own hands.

For the most part, we are all okay with having some day-to-day variation in our righteousness/holiness/moral life, as long as we know what the boundaries are that are “too far”. Nobody’s perfect, after all. Indeed, we would love to stay right there in the middle…neither too hot nor too cold.

But it turns out that Jesus doesn’t much care for that mindset. In fact, this desire to remain neither “hot nor cold” make Him want to, well, vomit (Rev 3:16).

The gospel of grace is not about “staying between the lines” or being “good enough”. When the rich young man asked Jesus what good deeds he must do to inherit eternal life, Jesus responded by saying, “If you would be perfect”…and then proceeded to lay down a series of impossible tasks.

The Gospel begins with a sobering realization: the understanding that God’s specification for eternal life is, “Be perfect as your Father in heaven is perfect”. The reality is that our natural variation from day to day only tells us how far below spec we are. We never get “good enough”, at any given moment.

This is perhaps why the Bible calls our righteousness is as unclean as filthy rags (Isa 64:6), that not even a single person has met this standard (Rom 3:10), and that even the best of us consistently fail to do the things that our spirits tell us we should be doing (Rom 7). Don’t get me wrong. The Scriptures are filled with examples of someone gaining God’s pleasure by giving sacrificially, loving radically, and obeying piously. We are made in His image, and are His prized creation after all. But those rare moments of greatness are ultimately proof of just how far below God’s standard we actually live, how far out of specification we are.

This sobering realization can be heartbreaking. (Indeed, it should be!) But the Gospel is born like a phoenix from the flames of this heartbreak: for it is only when we realize that we are hopeless to make ourselves right that we ever turn over our trust to God.

The Good News is that He has changed the rules. God, the great engineer who designed us and set our specifications, knows that we all fail to meet those specifications. He knows that the “heavenly bridge” cannot stand because the bolts are faulty. And so, He came up with a plan.

You see, I lied a bit above. I said that there were two options as an engineer if your parts are out of specification: either rework the parts or scrap and replace them. There is actually a third option: reinforce the structure with a stronger part to take the load off of the inferior components. Then you can “use as is” the inferior components, because the structural load has been given to the new, strong structural member. Perhaps you can see where I’m going with this: God took on human form and lived a life between the boundaries, perfectly in spec, and because of this, He can simply forgive us (“use as is”), joining us together with Him, through Christ (the stronger, new member who provides the structure).

Through his finished work on the cross, Jesus provides the strength of spirit that we were meant to provide. We do not have to work our way into specification: God is willing to “use as is”. All we do is trust Him, and stop trying to run our own lives. He uses us to build what He wants to build, praise God!