The following article contains spoilers from Action Comics #1047, on sale now.
Lex Luthor is gearing up for his latest battle with Superman. Action Comics #1047 (by Phillip Kennedy Johnson, Riccardo Federici, Lee Loughridge, and Dave Sharpe) saw him try to assess the battlefield, and see if there was anything Superman brought back with him that might be of use or a potential threat. What he found instead was a manifestation of all his worst fears and beliefs about Superman.
In Warworld's ravaged landscape, and its people's love for Superman, Luthor saw that everything he feared could become a reality. Luthor has always been ego-driven, but his belief that the Earth would look like Warworld by now had it not been for his presence indicates that he doesn't just hate Superman because he is better. He also fears what Superman could do with the trust people place in him. What's even worse is that Warworld validates these claims.
Luthor could never cope with the idea of being second best in anything. So, when Superman -- a man with the power of a god -- came along and chose to use his powers to defend the people instead of ruling them, it threw Luthor for a loop. However, it seems that behind all the jealousy is a certain fear of what Superman could accomplish, not just with his powers, but with the love and unconditional trust he has earned over the years.
Looking at Warworld, it's not hard to see why Luthor is scared. Superman arrived a total stranger, but through sheer force of will and charisma managed to convince the people to follow him into a war they did not ask for. As a result, countless amounts of people died. Earth could have suffered a similar fate had Luthor not done everything in his power to interfere with Superman's affairs. All of these thoughts must have been running through his head as he surveyed the carnage.
What drives the point home is that Superman is capable of making mistakes, and even becoming a despot. There have been several alternate versions of him who have led the world to complete destruction. Here though, Lex fears not what could happen if Superman took over by force, but if people willingly followed him. Warworld's current condition is an example of how Superman's leadership can lead to irreparable devastation and ruin.
However, this is all from Lex's perspective. He will always paint Superman in the worst possible light because of his ego. While Warworld was devastated by the revolution that occurred, its condition beforehand wasn't that much better. More to the point, the survivors who chose to follow Superman are free to live their own lives, not beholden to him in any way. They may honor him, but it is no different from how Earth honors a hero. What Luthor is stepping into is rubble, but it is also the foundation of a better future that came from believing in Superman.