Can you please help me understand what's going on in Malachi 3:16-18? Is this text saying God is pleased with those who think about Him and meditate about Him? Is it saying He rewards those who do so and fear Him?
"Then those who feared the LORD spoke to one another, and the LORD gave attention and heard it, and a book of remembrance was written before Him for those who fear the LORD and who esteem His name. "They will be Mine," says the LORD of hosts, "on the day that I prepare My own possession, and I will spare them as a man spares his own son who serves him." So you will again distinguish between the righteous and the wicked, between one who serves God and one who does not serve Him" (Malachi 3:16-18).
The book of Malachi records a number of grievances that God had against the children of Israel. Most ignored God, but there were some who listened. These were people who actually feared God; not like the arrogant who said, "It is vain to serve God; and what profit is it that we have kept His charge, and that we have walked in mourning before the LORD of hosts? So now we call the arrogant blessed; not only are the doers of wickedness built up but they also test God and escape" (Malachi 3:14-15). Those who feared God talked with each other, we must assume about their need to do better, and God took note of who wanted to serve Him. Their names were written in a book of remembrance, which is called the Book of Life in other passages.
It also mentions that they meditated on, thought about, or esteemed God's name. They were not a group that wanted to do right and then later forgot about it. They kept God and His laws in mind. "Do not let kindness and truth leave you; bind them around your neck, write them on the tablet of your heart. So you will find favor and good repute in the sight of God and man" (Proverbs 3:3-4).
God declares that He is going to take action against sinful Israel, which eventually led to the destruction of Jerusalem in A.D. 70, but God also said that He would spare those who were truly His people. After giving many warnings about the approaching destruction, Jesus said, "And He will send forth His angels with a great trumpet and they will gather together His elect from the four winds, from one end of the sky to the other" (Matthew 24:31).
Thus, God makes a distinction between the righteous and the wicked -- a distinction that we too must honor. There is a difference between those who serve God from their heart and those who do not serve God. At the core is whether they fear God or not. It isn't just thoughts, but it comes out in their actions.