I received this email:
A quick question for you. I believe you have said the Greek word for witness also means to bear testimony, to be a martyr, and to demonstrate. I have been spending a bit of time looking through the Greek on Biblehub and it is clear that testimony and martyr derive from the same word. However, I am not seeing any clear basis for your assertion that it also means to demonstrate.
One definition for the Greek word is to give evidence and you could presumably give evidence by way of demonstration. However, this doesn't seem to necessarily follow from the idea of giving evidence. I think the conventional interpretation would be that when you give evidence by witnessing of something, you give a report of (i.e., a testimony of) the thing as opposed to demonstrating the thing.
Granted, if you are testifying (or witnessing) to something about God, your testimony is going to be a lot more powerful if you actually live what you witness. Building on this, you could argue that the way you live is a form of a witness (or demonstration) of what you believe. This makes sense to me and so I can reason my way to the definition of witness as demonstrate. However, I can't find anything that explicitly makes this connection? Do you have any specific sources (other than direct revelation) that I can look to that more directly shows that witness can mean demonstrate?
Meta response
This is a great example of how when we have questions, we cannot tell what the answers require in faith, understanding, or sacrifice. You never know if what you seek requires a minute, a lifetime, or multiple to obtain. This poses tremendous opportunities if we find someone who knows (or can find out), but also great pitfalls if we take lightly the response given.
In all cases, the real reason we have an unanswered question, unserved need, etc., is always because we lack sufficient heed and diligence to obtain it. When we ask God for anything, we should always prepare our hearts by increasing our appraised value of what we seek. By presuming a question to be quick or a need to be a small favor, etc., we do the opposite and prime ourselves for underappreciating the result.
Asking, seeking, knocking--all of these things ought to center in our expansion of what we are willing to do, for how long, and how much we value what we are after. Again, this is the reason you don't already have what you are after. This applies to all contexts.
I don't say any of these things by way of criticism, just to teach a more important lesson than the answer to the question, knowing it is something we all grapple with, and almost all do without knowing it.
On this exact topic, I happen to have a video I recorded some time ago, but had queued to publish at a later date. I've moved up publication, and you can watch it here.
Response
I could only spend two hours putting this together, so apologies for the jaggedness and incompleteness of this response. It would take a whole book to adequately address this question.
There are no human words that unambiguously map to the gospel. Just as all rules fail to circumscribe all truth, human vocabulary will likewise have gaps where the words fail to accurately describe what is intended.
For those wanting to find more correct meanings in scripture, the shallow way of doing so is to look up words in the Greek dictionary and apply their meanings. There are tremendous treasures available for those who do this. It takes time, but you will be shocked at how common very simple and significant mistakes are made in all English translations. They all feature unforgivable errors.
The second level is to recognize words as variables. If you map every verse with a particular word, you can derive definitions from the context of the usage. When you compare this to the Greek dictionary definition, you will find abundant proof for my prior claim: that this is a case of pin-the-word-on-the-meaning, where authors/scribes/etc. had an idea and tried to find the closest word to it. In some cases, it's close enough. In others, it isn't.
The third level is to merge specific instances of specific words with different instances of different words, and continue the exercise of redefining these instances. This sounds complicated, but it isn't. You could draw a picture of how this works between two words with a simple Venn Diagram, where each area (the left, the middle, the right) gets a different definition.
Martyr
As the email stated, I have often said that martyr means many things, and each definition is important and related. These include testify, witness, to die for testimony, and to demonstrate. You will find the first three in the Greek dictionary, but not the last. The last would be in the center of the Venn diagram using the process described above. It is very important to understand the verses that would be more accurately translated with the English word "demonstrate." They are a key to understanding the importance of repentance, how critical following Jesus' example is to salvation, and how essential becoming like Jesus is to ministering in the gospel.
Jesus' works bore witness of him
Jesus answered them, I told you, and ye believed not: the works that I do in my Father’s name, they bear witness of me. (John 10:25)
This is an example of a very plain scripture that is made unclear by our tendency to quickly scan over words without stopping to ask what they mean. What is the Father's name? It is how he is. The works that Jesus did in the Father's name are the actions he took that demonstrated how the Father is, or the things he did that the Father would do in his place. Jesus said that these bore witness of him.
Can you testify of God without becoming like him?
The Holy Ghost testifies of God, but is not just a speaker about God. He is the record of heaven. He is engraved with the image of God.
For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one. (1 John 5:7)
This is the same witness we are to provide:
26 But when the Comforter is come, whom I will send unto you from the Father, even the Spirit of truth, which proceedeth from the Father, he shall testify of me:
27 And ye also shall bear witness, because ye have been with me from the beginning. (John 15)
Here, both testify and witness are the same Greek word.
Is it possible to testify of God without being like him? It is not.
You can testify that a dog is a dog without becoming a dog. You can’t testify that God is God without becoming like him. It would be as credible as believing a man who said he knew how to get rich, but was poor, or a man dying of cancer who claimed to have the cure.
If you truly believed, you would do, and if you don’t do, you don’t truly believe.
A key definition: to gain approval
One of the several meanings of Strong’s Greek 3140 martureó is "to gain approval."
2 For by it the elders obtained a good report (martureó, Strong’s 3140).
3 Through faith we understand that the worlds were framed by the word of God, so that things which are seen were not made of things which do appear.
4 By faith Abel offered unto God a more excellent sacrifice than Cain, by which he obtained witness that he was righteous, God testifying of his gifts: and by it he being dead yet speaketh.
5 By faith Enoch was translated that he should not see death; and was not found, because God had translated him: for before his translation he had this testimony, that he pleased God.
6 But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him. (Hebrews 11)
What is a good report? It is a testimony from God. Of what? Of similitude with himself.
What do we call Abel? A martyr. Why? Because God testified of him. What did he testify? That he was good; That he was like him.
God testified that Enoch pleased him. Can you please God except through righteousness?
God does not give a good report of those who are not actually good:
25 He that loveth his life shall lose it; and he that hateth his life in this world shall keep it unto life eternal.
26 If any man serve me, let him follow me; and where I am, there shall also my servant be: if any man serve me, him will my Father honour.(John 12)
It doesn’t matter what you say you believe. It is why you do what you do and what you do that matters.
Greek alternatives
A good question to ask is whether there are other words that could have been used rather than testify/witness/etc if "to demonstrate" was intended. I am not a Greek scholar, but from the poking around I've done, I haven't found one. Greek has several verbs that mean "to show," but they are all used scripturally to mean to prove, explain, etc., rather than to provide an example through one's own being.
Implications for repentance
People today think you can repent by merely asking forgiveness. You can’t. You actually have to change. If you remain the kind of person who would repeat sin, you cannot obtain forgiveness, no matter how often or urgently you ask.
You can’t be redeemed unless you change your works:
Neither did they receive any unto baptism save they came forth with a broken heart and a contrite spirit, and witnessed unto the church that they truly repented of all their sins. (Moroni 6:2)
And now, my brethren, I would that ye should humble yourselves before God, and bring forth fruit meet for repentance, that ye may also enter into that rest. (Alma 13:13)
But this cannot be; we must come forth and stand before him in his glory, and in his power, and in his might, majesty, and dominion, and acknowledge to our everlasting shame that all his judgments are just; that he is just in all his works, and that he is merciful unto the children of men, and that he has all power to save every man that believeth on his name and bringeth forth fruit meet for repentance. (Alma 12:15)
Wherefore, my beloved brethren, I know that if ye shall follow the Son, with full purpose of heart, acting no hypocrisy and no deception before God, but with real intent, repenting of your sins, witnessing unto the Father that ye are willing to take upon you the name of Christ, by baptism—yea, by following your Lord and your Savior down into the water, according to his word, behold, then shall ye receive the Holy Ghost; yea, then cometh the baptism of fire and of the Holy Ghost; and then can ye speak with the tongue of angels, and shout praises unto the Holy One of Israel. (2 Nephi 31:13)
Yea, and are willing to mourn with those that mourn; yea, and comfort those that stand in need of comfort, and to stand as witnesses of God at all times and in all things, and in all places that ye may be in, even until death, that ye may be redeemed of God, and be numbered with those of the first resurrection, that ye may have eternal life— (Mosiah 18:9)