What Is a Plumb Line in the Bible and What Does it Mean for Christians?

Everyone has a plumb line. You may not be aware of it, but it is there. A plumb line (or a plummet as it is sometimes called) is a weight hanging by a cord. Gravity ensures that the weight hangs perfectly straight, thus allowing a builder to ensure that a structure is vertically aligned. It is a simple but effective tool. 

Today’s equivalent is the modern level, and it is found in every toolbox or home-improvement kit out there. The level is used when aligning wallpaper, building retaining walls, or hanging pictures. The level ensures that the construction, art project, or decorating is correct, or “true to plumb.”

Scripture also speaks of plumb lines. God establishes a plumb line against, which Israel is to be measured.

Where Is a Plumb Line Seen in the Bible?

We see this in only a few Old Testament passages. The largest reference occurs in the book of Amos. Amos receives a vision of “the Lord standing by a wall that had been built true to plumb, with a plumb line in his hand.” 

The Lord explains to Amos that “I am setting a plumb line among my people Israel; I will spare them no longer” (Amos7:7-8). The plumb line heralds the oncoming judgment upon Israel. In fact, whenever scripture mentions a plumb line, we see this reference to oncoming judgment. 

• “I will stretch out over Jerusalem a measuring line used against Samaria and the plumb line used against the house of Ahab” (2 Kings 21:13).
• “I will make justice the measuring line and righteousness the plumb line; hail will sweep away your refuge, the lie, and water will overflow your hiding place” (Isaiah 28:17).
• “God will stretch out over Edom the measuring line of chaos and the plumb line of desolation” (Isaiah 34:11).

The plumb line is the image of God’s righteous and holy standard that Israel failed to embody in their lives. The plumb line physically represented Israel’s waywardness. Due to Israel’s failure to live “true to plumb” God brings about the necessary consequences of Israel’s sinful behavior. 

How do Christians interact with this image today? Given that the plum line appears to be an Old Testament image, we might wonder how useful this image is to Christians. After all, we live under grace, not law. Is the plumb line, therefore, still a helpful image? Does a plumb line still herald judgment upon God’s people, even considering the resurrection?

As Christians, we cannot discard the plumb line as an outdated metaphor simply because we find it in the Old Testament. The image of a plumb line is still applicable for us as we navigate our lives of faith. In fact, not only is this image useful for Christians. Understanding God’s plumb line also helps us live deeper and fuller Christian lives.

The Presence of a Standard

At its core, a plumb line is a standard against which other things are measured. Importantly, we do not create this standard. We do not make up the criteria by which things are measured. The plumb line is established by a greater force. It is the force of gravity that declares what is in plumb and what is not. The job of the builder is to base his or her project upon that unmovable standard.

When we think about our lives of faith, it can be easy to believe that a plumb line is somehow limiting or destructive. We see the presence of a standard against which “we are measured” as fundamentally condemning. Does God look at us with a critical eye, measuring out all our imperfections? Sadly, many people have this vision of God. 

What if, however, the presence of a plumb line is meant, not for condemnation, but encouragement? What if, instead of declaring the ways we “get it wrong”, a plumb line declares God’s vision for our lives? After all, we will always be out of plumb in some way. That is a fundamental part of human nature. 

We all have sinned and fallen short of the glory of God (Romans 3:23). The truth is, if there were no standard to which God’s people were measured, we could easily conclude that God is uninterested in our lives. This would leave us in chaos not freedom. The presence of a plumb line means that God has a desire for us. 

God desires that we live our lives immersed in divine love, grace, mercy, and forgiveness. To immerse ourselves in this reality, however, we must recognize where we step out of the flow of God’s divine love. What gets in the way of our spiritual life? 

What blocks us from experiencing the Holy Spirit? These questions can only be answered if there is a defining source to which we may go— a source of guidance and answer, a standard against which we can measure our lives. 

A plumb line is not about exposing our faults or wretchedness. Noticing where we have stepped awry of God’s way of love ultimately serves our repentance. It shows the way back and becomes a tool for our spiritual intimacy with God. The epistle of John declares “if we confess our sins, God is faithful and just to forgive us our sins and purify us from all unrighteousness” (1 John 1:9). 

Recognizing the places where we step out of God’s desire for our lives ultimately leads us to God’s infinite mercy and steadfast love. It is because God is faithful, loving, and just that we can be confident in placing our lives before God’s holy standard. 

A Reference to Build Upon 

A plumb line does not merely serve intellectual curiosity. Knowledge of a plumb line provides little help if a builder does not act upon it. A plumb line is to be referenced and built upon. Any builder, decorator, or hanger of pictures, who does not reference the vertical level puts an entire project at risk. When it comes to constructing a house, you do not want a builder who ignores the vertical plumb.

In the same way, we should not ignore God’s directions when it comes to establishing our spiritual lives. God’s standards of holiness, righteousness, justice, and love are to be practiced in our lives. These things aren’t just to be contemplated; we are to build our lives upon them. 

As Jesus lived, so too ought we. Jesus speaks about this in the closing section of his Sermon on the Mount. After teaching the inner nuances of discipleship, Jesus ends his discourse by appealing to wise and foolish builders. Jesus says,

“Everyone who hears these words of mine and puts them into practice is like a wise man who built his house on the rock. The rain came down, the streams rose, and the winds blew and beat against that house; yet it did not fall, because it had its foundation on the rock. But everyone who hears these words of mine and does not put them into practice is like a foolish man who built his house on sand. The rain came down, the streams rose, and the winds blew and beat against that house, and it fell with a great crash” (Matthew 7:24-27).

Jesus ends the Sermon on the Mount by speaking about the importance of heeding his words. Christ’s teachings are not simply quaint tales of morality. Nor are they delightful stories to tickle the ears. Christ’s words are to be incorporated into our lives. We build up our spiritual lives when we act upon Christ’s words in faith and obedience. 

God’s plumb line helps us remain spiritually healthy. Our spiritual livelihood needs a reference point that is stalwart and stable. Otherwise, we run the risk of erecting a spiritual life without a foundation. This leaves us clamoring about, attempting to find what works but never knowing where to begin. 

While we might think we a progressing, like the foolish builder who builds a house on sand, our spiritual lives easily come crashing down. Jesus clearly calls us to build our lives upon the foundation of his presence. In doing so, we are assured that our spiritual life is solid and secure.

What Is Our Plumb Line?

The Bible is the plumb line for the Christian life. It declares God’s loving delight for God’s people and discloses the Lord’s vision for the human life. Paul writes in his second letter to Timothy that “All scripture is God-breathed, and is useful to teaching, rebuking, correcting, and training in righteousness.” 

Like a plumb line, the breathed-out record of God’s word is a constant reference for us. Furthermore, if we find that we have erred or strayed, scripture declares the actions to be taken to rediscover God’s loving delight.

This is not a new understanding. The psalmist says the exact same thing in the heart of the Old Testament. Psalm 119 is the longest of psalms and is an extended meditation on God’s word. Famously the psalmist sings out “Your word, O lord, is a lamp unto my feet, and a light unto my path” (119:105). Scripture directs the life of faith. It is a source of constant reference and encouragement.  

A plumb line is a great image for the Christian's reliance upon holy scripture. The Bible is not an instruction manual, nor a compilation of stories and tales. Scripture is not merely to be read and then put away. God’s Word is to be incorporated into our lives. 

As we practice scriptural standards our lives become transformed; we reflect the glory and the presence of our risen Lord. Without a plumb line to declare what this looks like, and how this comes about, our spiritual lives are lost. Scripture helps us live true to plumb by uncovering, and inviting us into, God’s loving delight for our lives.

Photo Credit: ©Getty Images/megaflopp

The Reverend Dr. Kyle Norman is the Rector of St. Paul’s Cathedral, located in Kamloops BC, Canada.  He holds a doctorate in Spiritual formation and is a sought-after writer, speaker, and retreat leader. His writing can be found at Christianity.com, crosswalk.com, ibelieve.com, Renovare Canada, and many others.  He also maintains his own blog revkylenorman.ca.  He has 20 years of pastoral experience, and his ministry focuses on helping people overcome times of spiritual discouragement.