This week is a great example of why it is so valuable to read the Bible without regard for headings/verses/chapters that others add, and why it is so valuable to read a passage in context.
Generally, when someone quotes Matt 18:6, they use it to discuss the importance of having a sound Sunday School lesson. "Make sure you are teaching your kids the right things or you would be better off drowned!" But their failure to read 18:4 means that they miss the fact that Jesus is talking not about children literally, but about having childlike humility: bringing yourself low before God, putting trust in Him instead of yourself, seeking His glory and approval rather than your own. So Jesus is talking not about Sunday School teaching but about approaching His best followers, the "greatest in heaven" (v.1)-those who are humble and poor in spirit. The entire point that Jesus makes is further lost because verse 6 is separated from verses 7-9 because of headings added into the text by editors.
So let us read the entire statement that Jesus has made, after telling everyone to be as humble as children:
"Whoever receives one such child in my name receives me, but whoever causes one of these little ones who believe in me to sin, it would be better for him to have a great millstone fastened around his neck and to be drowned in the depth of the sea. Woe to the world for temptations to sin! For it is necessary that temptations come, but woe to the one by whom the temptation comes! And if your hand or your foot causes you to sin, cut it off and throw it away. It is better for you to enter life crippled or lame than with two hands or two feet to be thrown into the eternal fire. And if your eye causes you to sin, tear it out and throw it away. It is better for you to enter life with one eye than with two eyes to be thrown into the hell of fire." -- Matt 18:5-9, ESV
A good analogy for how lowly children were viewed would be to replace the word "child" above with "homeless man"--sort of the modern equivalent of the ultimate in lowly humility.
So here it becomes much more clear what Jesus said last week and this week. Let me paraphrase: "The greatest people in the kingdom of heaven are going to be those who were ignored, mistreated, and abused in this life. And whoever causes one of these lowly believers to sin will receive my wrath. How painful is our temptation to sin! We all face such temptations, but it is a great suffering to those who become tempted. Do whatever is necessary to avoid temptation. Even if you have to maim yourself, avoid temptation to sin. Avoid it at all costs."
This is perhaps a good paraphrase of what Jesus is saying here. He has established that those who are downtrodden and suffering are the ones whom God loves the most. From here He transitions into a thought about sinful temptation.
The book A Clash of Kings--the second book of the Song of Fire and Ice series--is the basis for Season 2 of HBO's Game of Thrones series. In the book, it is said: "To lead men, you must know them." Hebrews 4:14-15 tells us that Jesus is a leader to us because He knows what our lives are like.
Here, when Jesus is moaning about the temptation of sin, He is not just speaking out of ignorance! He knows what it is to see a beautiful woman and be tempted to lust. He knows what it is to have access to power and turn it down. He knows what it is to wish to flee God's plan and hide in fear. Yet though tempted, He did not sin. Jesus truly experienced these "woes". He knew just how painful they were.
This is why He is so forceful when He talks about being careful not to corrupt those around us with temptation--and to dramatically avoid those temptations ourselves. Because He knows exactly how painful the suffering of temptation can be.