According to Webster, a plumbline is a lead weight hung at the end of a line to determine whether a wall is vertical or straight; instrument used to test if something is vertical or straight; instrument to test if lines are true. Even in this age of laser instruments it is still used by carpenters, bricklayers and the like. It is still important that walls be vertical. We bought a house many years ago where the walls were not vertical and this sure did pose some problems in renovation.
God showed a vision to Amos in 7:7,8. He was giving him a message to deliver to Israel. The message was, in simple terms, I have set a standard before you to follow, and you will be judged by that standard. The tragedy in this instance is that God knew how they would measure up – cf. v.9 the high places of Isaac shall be desolate, and the sanctuaries of Israel shall be laid waste, and I will rise against the house of Jeroboam with the sword.
God tests His people and we remember how He tested Abraham (Gen. 22:1). God still tests His people and He still has a plumbline. The plumbline is Jesus (Matt.17:5) and the application is by His word (John 12:48).
He places the plumbline against our life. God expects us to walk by His rule; His standard. It is a different standard than that of the world. We are to deny ungodliness and worldly lusts and live soberly, righteously and godly (Titus 2:12). We are to abstain from every form of evil (1 Thess.5:22) and add to our life the Christian graces (2 Pet. 1:5-10).
He places the plumbline against our works. We are to let our light shine by good works (Matt.5:16) and we are to do good unto all men, especially unto the household of faith (Gal. 6:10). Not only does He hold the line against us as individuals, He does it congregationally: He told the congregations in Rev.2,3 “I know your works”.
He holds the plumbline against our worship. It is to be in spirit and truth (John 4:24), as well as decently and in order (1 Cor. 14:40). It is to include preaching (Acts 20:7), singing (Eph.5:19; Col. 3:16), prayer (Acts 2:42), the Lord’s Supper (1 Cor. 11:23-29), and giving (1 Cor. 16:1,2). Anything left out or added is not pleasing (cf. Gen. 4:1ff; Lev. 10:1,2; Matt.15:9)
He places the plumbline against each teacher. Since the gospel is the power of God unto salvation (Rom. 1:16) any modification of it will bring condemnation (Gal. 1:6-9. Men are prone to be “ear-ticklers”, preaching whatever pleases the masses, but true preaching is to include reproving, rebuking, exhorting with all longsuffering and teaching (2 Tim. 4:2-4).
He places the plumbline against our salvation. Numerous plans of salvation have been invented by men, but God only has one. It requires faith (Heb. 11:6 ), repentance (Acts 17:30), confession of Christ (Matt.10:32), culminating in baptism for the remission of sins (Acts 2:38).
I knew a fellow who used to wear a builder’s retractable tape measure on his belt when doorknocking (I must confess I have done the same). It was a bright fluro colour and so very noticeable. It appeared odd that someone would carry such a thing whilst doorknocking and so people would often ask, “Why do you have the tape measure?” His reply would be “To see how you measure up!’ There was a bit of levity in that, but then he would proceed to ask the person “How wide is your doorway?”. The person would have a guess and then he would guess something different. Then he would ask, “How do you suppose we could solve this confusion and know what the width really is?” The penny would drop and the person would recognize the authority of the tape – it could not be argued with! Even so, our world abounds in all sorts of religious doctrines that conflict with one another, and it is the Bible that is the measure of all things. How do you measure up against God’s plumbline?