Revelation 11:1-5
(Rev 11:1 KJV)
And there was given me a reed like unto a rod: and the angel stood, saying, Rise, and measure the temple of God, and the altar, and them that worship therein.

Now John is being asked to take a measurement. This is something which has been done in the past. Abraham was told to walk through the land which God was going to give to him.

(Gen 13:17 KJV) Arise, walk through the land in the length of it and in the breadth of it; for I will give it unto thee.

Now when we realize that God is not concerned about earthly real estate, we will know that God was using this walk of Abraham as symbolic because the real land of Canaan which God was going to give him was heaven which came through the eternal covenant.

(Gen 17:8 KJV) And I will give unto thee, and to thy seed after thee, the land wherein thou art a stranger, all the land of Canaan, for an everlasting possession; and I will be their God.

In Genesis 17:8, we read that God was going to give Abraham the land of Egypt and the land of Canaan for an everlasting possession. Now we know that this present earth will have an end and a new earth will come into being after the last day. Therefore, God is not speaking of present real estate but is promising Abraham eternal life in heaven or on the new earth which is the eternal possessions. Abraham walking around the land is just a figure of him receiving eternal life. Keep in mind that Abraham died and did not receive any of the land.

In Amos 7:7-8 God told Amos to look at the plumb line which He was using to measure the straightness of the people. They were found crooked and God told Amos that they would go into judgment.

(Amos 7:7-8 KJV) Thus he showed me: and, behold, the Lord stood upon a wall made by a plumbline, with a plumbline in his hand. {8} And the LORD said unto me, Amos, what seest thou? And I said, A plumbline. Then said the Lord, Behold, I will set a plumbline in the midst of my people Israel: I will not again pass by them any more:

Now back to Revelation 11:1. The reed which was given to John gives us no clue as to the length of it. The reed was something which was used for writing and also something which was cut and used for measuring. When Revelation was penned about 95 AD, the physical temple was already destroyed for 25 years, so this verse is not speaking of the Jewish temple but is speaking symbolically of the body of Christ which is called the temple.
(1 Cor 3:16-17 KJV) Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you? {17} If any man defile the temple of God, him shall God destroy; for the temple of God is holy, which temple ye are.

John is also told to measure the altar which is probably the altar of incense which we have already seen in previous verses. Then John is also told to measure those that worship within. This measuring could not be a literal measurement because there were an innumerable amount of believers already in Heaven and a great multitude of believers still on earth. The measuring here is nothing more than a symbolic action in which God is stating that He is totally aware of every believer on earth and in heaven. The measuring would be like a divine register of every believer which was written in the Lambís book of life. So this verse is in no way speaking of any future physical temple on earth because it is a symbolic gesture of the care of God for His believers.

(Rev 11:2 KJV)
But the court which is without the temple leave out, and measure it not; for it is given unto the Gentiles: and the holy city shall they tread under foot forty and two months.

Not only will the temple of God contain saved Jews, it will also contain saved Gentiles. The treading can be linked back to Matthew 11:12 which speaks of the Kingdom of God being taken by force.

(Mat 11:12 KJV) And from the days of John the Baptist until now the kingdom of heaven suffereth violence, and the violent take it by force.

It is speaking of the Kingdom of God advancing violently upon the world. The Kingdom of God invades the Kingdom of Satan and that is an act of violence when one kingdom comes against another. Whenever we advance the Kingdom of God, we are doing violence to the Kingdom of Satan by plundering it. The times of the Gentiles shall be on the last day.

(Luke 21:24 KJV) And they shall fall by the edge of the sword, and shall be led away captive into all nations: and Jerusalem shall be trodden down of the Gentiles, until the times of the Gentiles be fulfilled.

The holy city is another synonym for the body of believers. This has absolutely nothing to do with the physical city of Jerusalem which has now been set aside with the abolition of the ceremonial laws with the sacrifice of Christ.

The outer court which John is told not to measure speaks of the church on earth as it still continues to gather in believers and face the persecution which shall come in the New Testament period which is symbolized in the 42 months, which was also prophesied in Daniel 7:25. Then after the forty two months there will come a little space of time where it seems that Satan will have won and we will see this in a few verses.

(Dan 7:25 KJV) And he shall speak great words against the most High, and shall wear out the saints of the most High, and think to change times and laws: and they shall be given into his hand until a time and times and the dividing of time.

(Rev 11:3 KJV)
And I will give power unto my two witnesses, and they shall prophesy a thousand two hundred and threescore days, clothed in sackcloth.

On the heels of the forty two months prophesied in Revelation 11:2, the Lord Jesus tells John that the two witnesses are going to prophesy or preach the true Gospel for 1260 days. As the Kingdom continues to advance, God speaks of the body of believers and the local churches as the two witnesses. For it is only the saved in those churches who can be a commissioned witness for the true Gospel. In the law it was required that there be at least two witnesses for any matter to be established or legitimized.

(Deu 19:15 KJV) One witness shall not rise up against a man for any iniquity, or for any sin, in any sin that he sinneth: at the mouth of two witnesses, or at the mouth of three witnesses, shall the matter be established.

(John 8:17 KJV) It is also written in your law, that the testimony of two men is true.

God then says that He will give power to the two witnesses and they shall prophesy 1,260 days, which corresponds to the 42 months of Revelation 11:2. This period of time would represent the New Testament period minus the small amount of time which will occur between the last one being saved and the return of Christ. The fact that these witnesses are clothed in sackcloth means that they are calling the Elect to repentance. Only those whom God has qualified to hear and understand the Gospel will come to repentance.
(2 Tim 2:25 KJV) In meekness instructing those that oppose themselves; if God peradventure will give them repentance to the acknowledging of the truth; Repentance is a synonym for becoming saved and only the qualified Elect will repent and be saved. As we saw in the end of Chapter 9, that those unbelievers who were not affected by the plagues, did not repent of their sins (Rev. 9:21).

(Rev 11:4 KJV)
These are the two olive trees, and the two candlesticks standing before the God of the earth.

(Rom 11:17 KJV) And if some of the branches be broken off, and thou, being a wild olive tree, wert grafted in among them, and with them partakest of the root and fatness of the olive tree;

Now these two witnesses are being given two monikers. The first one they are given is that of the olive trees. In Romans 11, we read about the olive tree which is the body of Christ and how both Gentiles and Jews are grafted into the root and fatness of the olive tree. This olive tree is not the physical nation of modern Israel because that nation is not mentioned in Scripture.

(Rev 1:20 KJV) The mystery of the seven stars which thou sawest in my right hand, and the seven golden candlesticks. The seven stars are the angels of the seven churches: and the seven candlesticks which thou sawest are the seven churches.

Then the second moniker it is given is that of the candlestick which we saw in Revelation 1:20 as the seven churches. If you remember, that the seven churches represented all the churches down through the ages until the last day. Even though we are seeing many churches falling to false gospels, yet there is a remnant of faithful churches which are still in existence. However, that will come to an end very shortly right before the return of Christ. If Satan can successfully attack the local churches and turn them to false gospels, then he will be able to discredit all of Christianity as true Christians are normally tied to the church. The church is a part of the testimony of the true believer.

(Rev 11:5 KJV)
And if any man will hurt them, fire proceedeth out of their mouth, and devoureth their enemies: and if any man will hurt them, he must in this manner be killed.

In previous verses, God had stated that the plagues and judgments would fall upon the unbelievers of the world and that the believers are spiritually protected by being part of the heavenly temple which John was told to measure. What God is pointing out here is that His children are under His protection and if anyone harms them, then fire will devour those who attempt to hurt them. This fire will be evident on Judgment day when the unbelievers and the persecutors will stand before the Lord and give an account for their hatred of Christ and Christianity. This, of course, does not rule out the fact that unbelievers will suffer judgments from God on earth as they attempt to hurt the believers. These judgments will be designed to give the believers temporary respite so they can continue to send forth the Gospel until the last day and then comes the final fiery judgment of the unbelievers. The fact that these unbelievers will face the same type of judgments that they will try to foster on the believers goes back to the principle of the Golden Rule.
(Mat 7:12 KJV) Therefore all things whatsoever ye would that men should do to you, do ye even so to them: for this is the law and the prophets. The Golden Rule does not only apply to good but it also applies to the evil people. As they have fought against Christ and the Gospel, then they will face the consequence of their actions. In other words, no unbeliever will get away with anything. As they have persecuted and attempted to do harm to believers, they in turn, will likewise receive proper judicial compensation for their crimes.