What is a plumb line in the Bible?

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TL;DR:

A plumb line is a tool used to determine if something is aligned. God’s Word is our plumb line that aligns our hearts and lives with His will.

from the old testament

  • In Isaiah 28:16–17 God references a plumb line, saying, "Behold, I am the one who has laid as a foundation in Zion, a stone… And I will make justice the line and righteousness the plumb line." God says that justice and righteousness are the standard by which His people will be measured.
  • When God sent Amos to warn Israel about the impending judgment due to their corruption, He said, "Behold, I am setting a plumb line in the midst of my people Israel" (Amos 7:8). This symbolic plumb line is the standard of justice and righteousness with which God's people were to align themselves.
  • Proverbs 21:8 says, "The way of the guilty is crooked, but the conduct of the pure is upright." A plumb line would expose anything that is crooked.
  • Psalm 119:9 asks "How can a young man keep his way pure?" then answers, "By guarding it according to your word." God's Word is the only true standard we have for assessing our actions. In fact, two verses later the Psalmist says, "I have stored up your word in my heart, that I might not sin against you" (Psalm 119:11). God's Word reveals God's standards.

from the new testament

  • As Paul explained to Timothy, God’s Word is "profitable for teaching, for reproof, for correction, and for training in righteousness, that the man of God may be complete, equipped for every good work" (2 Timothy 3:16–17). The Word of God reveals the plumb line against which we will be measured.

implications for today

God calls His people to "be holy, for I am holy" (Leviticus 11:44, 45) and yet, "all have sinned and fall short of the glory of God" (Romans 3:23). While we rely on the Holy Spirit to use God's Word to work in our hearts and for that work to manifest in our actions, we can rest assured that everywhere our lives don't align with God's plumb line we can be "justified by his grace as a gift, through the redemption that is in Christ Jesus" (Romans 3:24). The plumb line of God's standards points us to our need for Christ and His sanctifying work in our lives.

God's Word is as our plumb line, the unerring standard against which we measure our lives. In Isaiah 28:16–17, God establishes justice and righteousness as His foundational principles, declaring them the plumb line by which His people are evaluated. Therefore, as we align ourselves with God's Word, we find clarity and correction, ensuring our lives are upright and truly walking in God’s ways.

understand

  • God's plumb line sets justice and righteousness as His measuring standards.
  • God’s plumb line exposes crookedness and guides towards purity.
  • God's Word reveals our plumb line.

reflect

  • What does God’s plumb line reveal about His character?
  • How does understanding God's plumb line affect your daily decisions and actions?
  • How can you deepen your reliance on God's Word as your ultimate guide and plumb line?

engage

  • A plumb line is a tool used by builders and painters to find the true vertical. A plumb bob, typically a pointed lead weight, is suspended from a string and gravity then makes the string hang perfectly straight. Thus, the builder can ensure that the structure he is constructing is erected perfectly true and the painter can use it as a reference line. The plumb line has since been replaced by more modern levels; however, it is still an effective tool.
  • How does the concept of God's plumb line challenge cultural and societal norms today?
  • How can we align ourselves with God's plumb line of justice and righteousness in our community?