Revelation 9:20-21

²⁰ And the rest of humanity who were not killed by these plagues even then did not repent of [the worship of] the works of their [own] hands, so as to cease paying homage to the demons and idols of gold and silver and bronze and stone and wood, which can neither see nor hear nor move.

• The rest of the world, the unsaved not the countless members of the Church, will continue to pay homage to worldliness during the end times. Either through false Christianity, other religions, their own efforts, or capitalism. The hot are hot and the cold are cold, there will no longer be any lukewarm. 
• Notice that John sees that they worship the works of their own hands. This ties right in with during the last days men will be greedy, lovers of self, prideful, and arrogant, 2 Timothy 3:2.
• People will have an inordinate love of gold, silver, and other worldly things during the Great Tribulation. This means that there has to be these things, if there wasn't people would be seeking, food, water, and shelter, the basic needs of life. 
• There is a huge push for people today to buy gold and silver to protect themselves from the possibility of a collapse of the world's economy. These people are not greedy, they are supposedly being  prudent, but they are trusting in the world and not God. People are not changing their way of thinking, they trust in the world, this will only increase during the end times. Now for this to increase, there must be gold and silver to be had, during the Great Tribulation.
• Jesus told us to think like the birds who neither gather or store and yet are taking care of by our Father: the Sermon on the Mount. 
• If the world had actually lost all of its green grass, a 1/3^rd of its trees, and every living thing in the sea, people would care less about gold, silver, and worldly things. They would need food and water so that they could survive, not gold and silver to prosper. 
• If all of the things that we are warned about in in Revelation are physical then people would be flooding to God, as people always have during times of trouble. But in times of prosperity, people run away from God. They turn to profane desires, lust, and self. So the warnings must be spiritual in nature and not physical for people to still desire gold and silver.   

²¹ And they did not repent of their murders or their practice of magic (sorceries) or their sexual vice or their thefts.

• Basically what we are shown here is that people need the Truth.
• Remember too that people can only repent because our Father enlightens them with the Truth so that they can repent. There is a time when every knee will bow and every tongue will confess the Truth and be set free. Many will repent during the Great Tribulation, but some will have to wait until the last day to do it. But amen, Jesus was very successful at the Cross and He will give eternal life to all that He has been given and He has been given all, John 17:2.
• And this is eternal life: [it means] to know (to perceive, recognize, become acquainted with, and understand) You, the only true and real God, and [likewise] to know Him, Jesus [as the] Christ (the Anointed One, the Messiah), Whom You have sent. John 17:3