There are a lot of things that could be addressed in the link. I just want to go over a few things, to show you the way the author interacts with scripture.
The first thing to notice is the type of language used in the article: overuse of words like "obviously," "astonishing," "staggering" and "shocking," and the "wait, but there's more!" type language makes it read like an infomercial. In an infomercial, the author tries to convince you that you need the product, but the cost of the product isn't revealed until they think you've already bought it in your mind. The layout of the article works the same way, promising
"Knowledge of your awesome potential—your incredible future—has been kept from you!" until late in the article, the cost is finally revealed where the author says:
"Thus, the Bible teaches there is one God, composed of two Persons—the Father and Christ—with many more persons to be added later..." right before the author explains that the condition of entering the kingdom is whether or not you have followed the law your whole life! The thing you should understand from that is this: the article you've read is written in persuasive language -- while you're reading it, you should be keeping in mind that the author is posting scriptures, but using tactics of persuasion to try to make himself appear correct about the ways he's interpreted those scriptures.
Jewish people believed in what they called (and still call) the Messianic Age, and they had this certain list of expectations about what the Messiah would do when he came. Jesus spent a lot of His ministry basically wrecking everything they believed about what Messiah would do. When something He said starts out with something like "The kingdom of God is like..." basically He's saying, "You think you know what the Messianic Age will be like? Here's what it's
really like..."
So here is something from the link you posted:
"The answer is an emphatic “No!” But most preachers teach that the gospel of Jesus Christ is about Christ, also claiming that He is the kingdom of God and that the gospel of the kingdom is Christ. We have seen that this is false, and completely unbiblical!"
And here's what Jesus said about the kingdom:
Luke 17:20-21
Once, on being asked by the Pharisees when the kingdom of God would come, Jesus replied, “The coming of the kingdom of God is not something that can be observed, nor will people say, ‘Here it is,’ or ‘There it is,’ because the kingdom of God is in your midst.”
The author of the article writes:
Christ said, “My KINGDOM is not of this world [this present society]” (John 18:36)
Note that the author adds [this present society] to the text to explain "not of this world" instead of simply listening to Jesus, who says "The coming of the kingdom of God is not something that can be observed.. the kingdom of God is in your midst."
The author of the article writes:
"So let’s understand. The word “kingdom” simply means government. Of course, you cannot have a government without a nation to govern. Therefore, a kingdom is at least one nation with a government.
There are four necessary components to any kingdom: (1) Land, property or territory—however large or small. In other words, one must have a specific and definite set of boundaries constituting the size of the kingdom; (2) a ruler, king, monarch or governor leading the government; (3) people or subjects living within the territory; and (4) a system of laws and rules along with a basic structure of government. No kingdom is complete without all of these fundamental elements."
The author makes a dangerous assumption: that when Jesus says the word "kingdom," that means we can use what we observe about earthly kingdoms, and take that information to speculate about what God's kingdom should be like. In the Bible, Jesus is explaining to people why they were wrong in speculating about God's kingdom, because God's kingdom isn't like earthly kingdoms. The author of the posted article has made exactly the same error: speculated about the nature of God's kingdom based on what he has observed about earthly kingdoms, instead of just listening what Jesus had to say.
When the Bible says that "
17For God did not send his Son into the world to condemn the world, but to save the world through him.
18Whoever believes in him is not condemned, but whoever does not believe stands condemned already because they have not believed in the name of God’s one and only Son" (John 3:17-18), we should be outright rejecting a "gospel" which says that
"The Message—the centerpiece—of the gospel is not Christ," and that people are deceived
"By focusing on Him..." That's plainly not the case. Focusing on Christ will keep you savvy to when you're hearing a false gospel.
So yes, the kingdom of God
is prophesied in the prophets, but let's learn about what that means from Christ's teachings, and not from speculating about what it might be from what we observe in earthly kingdoms, or we'll be as wrong as the people in Jesus' day were when He had to set them straight.