To witness and to give you assurance of these things. Revelation 22:16.

 Why did Jesus have to remind John that His words are meant to give assurance of these things?

Because, He knew, somewhere down the road, that the enemy and those that follow the voice of the enemy will play into the enemy's hand and do their best to disenchant and distract you; and you will stagger at God's promise, our hope of heaven and a life with Christ.

Hear what Jesus said.

Revelation 22:16 AMP “I, Jesus, have sent My messenger (angel) to you to witness and to give you assurance of these things for the churches (assemblies). I am the Root (the Source) and the Offspring of David, the radiant and brilliant Morning Star.” [Isa. 11:1, 10.]

Since the Revelation spent a tremendous amount of time spelling out the horrors. The Prophet Isaiah also spends a good deal of time, but in this case, it spells out the beauty and the benefits.

“And the wolf will dwell with the lamb, And the leopard will lie down with the young goat, And the calf and the young lion and the fatling together; And a little boy will lead them. Also the cow and the bear will graze, Their young will lie down together, And the lion will eat straw like the ox. The nursing child will play by the hole of the cobra, And the weaned child will put his hand on the viper's den. They will not hurt or destroy in all My holy mountain, For the earth will be full of the knowledge of the LORD As the waters cover the sea. Then in that day The nations will resort to the root of Jesse, Who will stand as a signal for the peoples; And His resting place will be glorious.”
(Isaiah 11:6-10 NASB)

Allow me to ask you a few questions.

Does the wolf dwell with the lamb, or does the leopard lie down with the young goat? How about the little boy leading them all?

Not a chance, as yet, but it will happen when the millennium begins. Isaiah tells us that “they will not hurt or destroy in My holy mountain,” and although there are references to Jerusalem being God's holy mountain, during the millennial reign His mountain will be in the center of it all.

Why?

Because the earth will be full of the knowledge of the Lord. This statement just as easily could say, “The End,” but it doesn't; it prompts us to visualize the vastness of the ocean by saying, “as the waters cover the sea.” Try to imagine this, in all the areas in which the waters make up the sea, are there any holes through which you could look through and see the sea bed? That borders on the impossible. Well, this is how God sees the knowledge of who He is, His nature, and His character.

Full seems like such a simple word. If I filled a pitcher with water, it would be assumed that you could not, reasonably, put any more liquid in the pitcher. If you look the word up in Hebrew you will find that there is more to it than that. There are two possible spellings of mâlê', maw-lay' and mâlâ', maw-law' but the meanings do not change. The Word Study Dictionary only focuses on mâlê. While full is typically first on the list there is also fulfill, to finish, and to satisfy.

So if I changed one word in the sentence “For the earth will be full of the knowledge of the LORD As the waters cover the sea,” A simple word can change the impact and meaning of the sentence, and, since we are aware that there are known issues with many of the Bible translations, it could be that God wanted us to open our eyes and read it in the alternative form, “For the earth will be satisfied with the knowledge of the LORD As the waters cover the sea.” Currently, there is no way you could say that.

Some details from Revelation 22:16, and to do that I will put the verse before our eyes once again.

“I, Jesus, have sent My messenger (angel) to you to witness and to give you assurance of these things for the churches (assemblies). I am the Root (the Source) and the Offspring of David, the radiant and brilliant Morning Star.”

• Who is doing the talking?

  Both Jesus and an angel messenger.

• Why are they talking?

  To bring a witness.

  Ah, but a witness of what? A witness is often an eyewitness of an event or substantiation of something overheard. In either case, you should be able to understand why God emphasized two or more witnesses.

  Since the prophetic, to the Jew, and this includes the Apostle John, is a repeated pattern. Why is this repeated pattern so important? Because the prophecies given by say, Daniel, Isaiah, and Ezekiel, just to mention a few, are now being repeated in Revelation. The law said that NO single witness is capable of bringing about a conviction of a crime; there had to be two or three, and we have, in many cases, three witnesses.

  And to give you assurance of these things …

  Give me a moment, and I will finish the sentence, but first I want to point something out. We are bombarded, mostly by the mouths of religious zealots, although they don't see themselves that way; who will say to you, why do you persist in talking about these things; this, in their minds, is important because some of us, have been preaching the soon return of Jesus for over two thousand years. I suppose their statement implies that we are wasting our time. Do you find any assurance in attacks like that? No, I don't, either. A worship song has the line in it, I remind myself of all that He's done. Why would I repeatedly remind myself of all that He has done? Because we forget after time; because people will try to verbally beat the sound word out of you.

  What does the word assurance mean? The reality is that most of us reading this have an idea of what assurance means. Many might say this tells me that I can trust the person or witness standing before me. Webster's dictionary defines assurance as:

  1. The act of assuring, or of making a declaration in terms that furnish ground of confidence; as, I trusted to his assurances; or the act of furnishing any ground of full confidence. 2. Firm persuasion; full confidence or trust; freedom from doubt; certain expectation; the utmost certainty. 3. Firmness of mind; undoubting steadiness;

  The dictionaries definitions exude confidence. Now, internally, take a poll.

  How many of those people in your mental poll have a confident hope and assurance of what God has in store for them? Not very many were there.

  For the believer, the fulfillment of this hope and this life with the Father begins with the catching away of the church. For those who come into a relationship with Jesus during the time of wrath, it begins with their death during the seven years. millennial reign.

Why do you suppose (assuming that many of these heard the message of hope) they could not grasp the hope and make it theirs? 

Do you think it is merely the cares of this world, or has Satan blinded their eyes so that they cannot perceive the hope afforded to the believer in Jesus?

Maybe it is the faulty teachings that remind us that we are sinners and, therefore, not worthy of the Father's love.

All these questions are irrelevant if you have a tongue that can speak, eyes that can see, or a hand that can express the character and nature of the loving God that waits for us.

I wrote out a portion of verse sixteen and said, give me a moment, and I will finish the verse. That moment is here.

“ to give you assurance of these things for the churches.”

The messenger, even if it is me or the Word of God which you may have stumbled upon, is giving witness to and testifying that these things spoken about Jesus, the Father, heaven, our salvation from the wrath that is to shortly come, are our hope and promise. Our directive is to share this information, as best you can, with the church. I have thought about these things (as I remind myself of all that He has done,) and I am confident that you should also. These things are the evidence we have where Jesus fulfilled His promises about rising from the dead and that He would come back and collect His bride and take that bride back to the Father.

If you are in relationship with Him, then you too are His bride.