The sin of substitution has always been a problem. Men have invariably tried to substitute their opinions for Divine commands. Two Old Testament priests, Nadab and Abihu, "offered profane fire before the Lord, which He had not commanded them" (Leviticus 10:1). God struck them dead because they substituted the fire He had specified for a fire of their own choosing. Instead of offering a bleeding lamb, Cain substituted the fruit of the field (Genesis 4:1-8) and God rejected his offering. At the water of Meribah, Moses the Lord's plan with his own. Instead of speaking to the rock, Moses decided to smite it. God considered his actions to be an act of unbelief (Numbers 20).
Has modern man learned from these events which "were written for our learning" (Romans 15:4)? I don't think so. Even Christians are sometimes guilty of this crime.
As we apply the Great Commission (Matthew 28:18-20), we are commanded to "teach all nations." This part of the command was not just for the apostles, preachers and elders, but all disciples.
To "teach" you must "give instruction" and "impart knowledge." In far too many congregations the "teaching" of the lost has been neglected. While feeling guilty about their lack of ability to "instruct" the lost, some brethren have offered a substitute plan: have someone else do the teaching for them. The sin of substitution!
The plan usually works something like this: a few Christians get together and canvas a neighborhood inviting the lost to attend services and there receive instruction from the preacher. I would never discourage anyone from inviting non-Christians to the assembly; I wish more brethren would do this very thing. However, we must remember that even if we personally invite every person in town to our meetinghouse, we have still not fulfilled the Great Commission! We are commanded to teach the lost, not just invite them to services.
Why do brethren attempt to substitute their plan for God's? I suppose it is because most people do not feel competent enough to teach. This is a lame excuse. Anyone who has obeyed the gospel of Christ should be able to tell how they became a Christian and give book, chapter and verse to back it up. They might not be able to answer every quibble raised by denominational preachers, but they can present the facts of the gospel.
Brethren sometimes ask me to go visit a friend or relative of theirs in the hope of setting up a Bible study. I am always happy to do this. However, I remind them that if they have no influence with their friends and relatives, I doubt that I will have any either. God's plan is for you to first live the gospel and then teach it to your neighbors.
Paul instructed Timothy to "do the work of an evangelist" (2 Timothy 4:5). This includes study, meditation and preaching of the word. Timothy was to "convince, rebuke (and) exhort with all longsuffering and teaching" (2 Timothy 4:2). Paul also said, "the things that you have heard from me among many witnesses, commit these to faithful men who will be able to teach others also" (2 Timothy 2:2).
Brethren, we all need to sharpen our teaching skills. Let's not deceive ourselves into thinking God will approve of a substitute plan for teaching the lost.