This answer was taken from https://www.biblebookprofiler.com/ephesians-3-9-forgery.html
Copied and pasted with some ommission.
11 Felony Forgeries against Jesus Christ in the bible
Introduction
What truths do the ancient biblical manuscripts of Ephesians 3:9 reveal?
7 questions you need to ask if you believe that Jesus actually existed in Genesis 1:26
What does the companion reference bible say about Ephesians 3:9?
What do 8 different commentaries say about Ephesians 3:9?
11 Point Summary
INTRODUCTION
Some christians say that Jesus Christ was in the beginning with God, helping him create the universe, or some variation of that. But how can that be??? Wasn't he born around 2,000 years ago in Bethlehem? One of the verses used to "prove" that he helped God create the universe is Ephesians 3:9
Ephesians 3:9 [KJV]
And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:
This verse certainly seems to support the idea that Jesus did indeed create the universe. Unfortunately, most christians will read this verse, come to the same conclusion and move on with the wrong doctrine that Jesus created the universe, but this contradicts Genesis 1:1
Genesis 1:1
In the beginning God created the heaven and the earth.
There are only 2 logical options that I can see: either Jesus is also God, or something is wrong with this verse.
One of the ways that the bible interprets itself is that all verses on the same subject must be in harmony and agreement.
Isaiah 44:24
Thus saith the Lord, thy redeemer, and he that formed thee from the womb, I am the Lord that maketh all things; that stretcheth forth the heavens ALONE; that spreadeth abroad the earth BY MYSELF;
hus Isaiah 44:24 proves not once, but TWICE that Jesus Christ was NOT with the father in the beginning to help him create the heavens and earth.
Isaiah 44:24 is internal evidence of the correct translation of all the ancient manuscripts of Ephesians 3:9.
To get to the correct answer, we must dig a little deeper into the word of God and find the truth. You see, we don't have the original biblical manuscripts. They have been lost or destroyed a long time ago. However, using the principles of how the bible interprets itself and all the existing manuscripts we do have, it is still possible to get back to the original truth God spoke and had written down.
How do the ancient biblical manuscripts render Ephesians 3:9?
Nestle 1904 Greek interlinear of Ephesians 3:9
"And to enlighten all what [is] the administration of the mystery having been hid from the ages in God the [one] having created all things".
As you can see, the phrase "by Jesus Christ" is not in the Greek text [Nestle 1904], but what if this Greek text is wrong? Then we can verify it by going to another one.
Look at this screenshot of the Mounce Reverse Greek/English Interlinear text.

Well isn't that interesting? This Greek interlinear agrees with the Nestle 1904 text. We could conclude that this verse was tampered with to promote a theology, but we're not going to stop there since I don't like to leave any doubts whatsoever.
Look at this screenshot of the Codex Sinaiticus, the oldest complete Greek New Testament in existence, dating back to the 4th century. As such, its one of the most authoritative biblical manuscripts on the planet and everybody with internet access can see it for free!

As you can see from the screenshot below, the Lamsa bible, from the ancient Aramaic Peshitta manuscript dating back to the 5th century does not have the phrase "by Jesus Christ" in it.

See the screenshot below of St. Jerome's Latin Vulgate text of 405A.D. on the Felony Forgery of Ephesians 3:9 [If you are using Google chrome, just right click and choose the translate option or use translate.google.com].

Screenshot of the Armenian bible from the Syriac text of 411A.D. on the Felony Forgery of Ephesians 3:9 [including the google translate version of "dispensation" to "economy" LOL Its not perfect, but its not going to delete "by Jesus Christ", even if it were there].

The NET BIBLE is a completely new translation of the Bible! It was completed by more than 25 scholars – experts in the original biblical languages – who worked directly from the best currently available Hebrew, Aramaic, and Greek texts.
Check out the screenshot below of the NET bible of Ephesians 3:9!

5 different modern bible versions in parallel
Furthermore, at least 5 other modern versions do not have the phrase "by Jesus Christ" in it.
So there you have it - the phrase "by Jesus Christ" was added to the King James version of the bible many centuries after the bible was already written. If this error was simply the issue of mistranslating a letter or two from an old, damaged or excessively worn manuscript, I could say that this was an honest mistake, but unfortunately, we can't say that.
How much more evidence do we need?!
How is it possible to accidentally add 3 words to the end of a verse when none of the previous ancient manuscripts have them, regardless of language or geographical location?
We must change our thoughts and beliefs to match what the word of God says rather than decide what we believe first and then try to manipulate verses to fit our belief systems.
WHAT DOES THE COMPANION REFERENCE BIBLE SAY ABOUT EPHESIANS 3:9?
Verify for yourself the Felony Forgery of Ephesians 3:9 from the screenshot below of E.W. Bullinger's Companion Reference Bible; notes on Ephesians 3:9 [If you go to this site, go to page 6].

What do the commentaries say about Ephesians 3:9?
Commentaries on Ephesians 3:9
Ellicott's Commentary for English Readers
"The words **“by Jesus Christ” should be omitted, probably having crept in from a gloss, and **not belonging to the original
Barnes notes of the bible
"But the phrase is missing in the Vulgate, the Syriac, the Coptic, and in several of the ancient mss. Mill remarks that it was probably inserted here by some transcriber from the parallel passage in Colossians 1:16; and it is rejected as an interpolation by Griesbach."
Jamieson-Fausset-Brown Bible Commentary
"The oldest manuscripts omit "by Jesus Christ."**
Gill's Exposition of the Entire Bible
"The phrase, "by Jesus Christ", is left out in the Alexandrian and Claromontane copies, and in the Vulgate Latin, Syriac, and Ethiopic versions".
Meyer's NT Commentary
"When διὰ Ἰησοῦ Χριστοῦ [by Jesus Christ] is recognised as not genuine (see the critical remarks),"**
Expositor's Greek Testament
"but these words must be omitted, as the best authorities ([285] [286] [287] [288] [289] [290], 17, etc.) do not give them."**
Cambridge Bible for Schools and Colleges
"Omit “by Jesus Christ,” with the preponderance of ancient authority".
Pulpit Commentary
The words, by Jesus Christ (A.V.), are not found in a great preponderance of textual authorities.
SUMMARY
The majority of the critical Greek texts do not have the phrase "by Jesus Christ" in Ephesians 3:9
The Codex Sinaiticus, one of the oldest and most authoritative Greek manuscripts in the world, does not have the phrase "by Jesus Christ" in Ephesians 3:9
The ancient Latin Vulgate text of 390-405AD written by st. Jerome, does not have the phrase "by Jesus Christ" in Ephesians 3:9
The ancient Aramaic Peshitta manuscript dating back to the 5th century does not have the phrase "by Jesus Christ" in Ephesians 3:9
At least 5 other modern bible versions do not have the phrase "by Jesus Christ" in Ephesians 3:9
On page 6 of the Ephesians file of the online companion reference bible, the note on verse 9 says regarding the phrase "by Jesus Christ" - "all texts omit"
In Genesis 1:26, the words "us" & "our" are the figure of speech majestic plural, also known as the royal we. It is the use of a plural pronoun to refer to a single person or entity holding a high office, such as a king or sultan. Its to emphasize their supreme greatness, majesty and royalty.
The dating of Genesis 1:26 means that Jesus' own mother had not been born for thousands of years, so how could Jesus exist before he existed [was born?]
Regardless of theology, at least 8 different bible commentaries are all in agreement that the phrase "by Jesus Christ" is not in the vast majority of biblical manuscripts and none of the most ancient ones, admitting that it was added to the bible.
All the above evidence proves that the phrase "by Jesus Christ" that was added to the end of Ephesians 3:9 was a deliberate forgery.