What significance do you think God places on His instruction? Don't you find it of interest that as Moses teaches the law and statues God gave him on Mount Sinai, he inserts this warning? He tells the Israelites not to add or subtract from the commands the LORD God gave. Moses’ warning inferred that by adding to or subtracting from God's law, they would be unable to keep it.
In the Sermon on the Mount (Matthew 5-7), Jesus deals with this subject. After telling the listeners who would be blessed by God, Jesus explicitly tells them He did not come to abolish the Law or the Prophets but to fulfill them. Then, He says the heavens and earth will pass away, but the smallest dot of the Law would remain until it is all accomplished. Five separate times in Matthew 5 Jesus uses the phrase "You have heard...But I say" to correct the Jew's understanding of God's Law. They had done what Moses had warned them not to do and in the process, they were not keeping God's instruction.
Eve did the same thing when speaking to the serpent in the garden. Eve added to God's instruction in her response to the serpent's question, "Did God actually say, 'You shall not eat of any tree in the garden'?" God had instructed Adam and Eve not to eat of the fruit of the tree of good and evil, but Eve added: "neither shall you touch it, lest you die."
Isn't that human nature though? Aren't we okay adding to the law if it is something we know won't be a problem for us to obey? And don't we tend to subtract from the law if it something we are tempted to do or want to do? I am pretty good at not doing those things which don't tempt me, but if the temptation is there, I would rather avoid the command not to participate.
When we get to the end of Revelation, you will see John gives similar instructions to those Moses gave, with a dire warning attached. Revelation 22:18-19 says, "I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, and if anyone takes away from the word of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book."
There is a set pattern in John's seven letters. Each letter begins with a unique description of Jesus. Following this description is Jesus' comments for each church: His praise, His rebuke, His command, His discipline, and His promise. You will notice some churches do not receive comments for each section.
Using the letter to the church at Ephesus as an example: First, Jesus identifies Himself. To Ephesus (Revelation 2:1-7) He says He is the one who holds the seven stars in his right hand, who walks among the seven lampstands. He begins with His praise to the church in verses 2-3, His rebuke in verse 4, His command and discipline are in verse 5, with His promise in 7. As you study, you will find my categories are not an exact science, but I pray and believe they will be helpful in your study of these chapters.
P.S. As I suggested yesterday, it will be well worth your time to either highlight or list the names and descriptions of Jesus in Revelation.