Beginning with the last book in the New Testament, Jude, who wrote the letter, wrote: "And Enoch also, the seventh from Adam, prophesied of these, saying, Behold, (b) the Lord cometh with ten thousands of his saints, To execute judgment upon all, and to convince all that are ungodly among them of all their ungodly deeds which they have ungodly committed, and of all their hard [speeches] which ungodly sinners have spoken against him. These are murmurers, complainers, waling after their own lusts; and their mouth speaketh great swelling [words], having men's persons in admiration because of advantage." (Jude 1:14-16)
"In this passage, Jude quotes from the apocryphical Book of Enoch. Although this book was not included in the canon of Scripture, early church historians wrote that the church accepted it as a valid source of information. Therefore, it is plausible that Jude, writing under the inspiration of the Holy Spirit, used this prophecy of Enoch as a means of describing those false teachers who sought to lead astray believers from the true faith in Christ." (Note p. 1557 Hebrew Greek Key Study Bible, KJV)
In determining who the 10,000s Saints are, we have to interpret Scripture with Scripture. The references given (b) are Deut. 33:2; Dan. 7:10; Zech. 14:5; Matt. 25:31
In Deuteronomy 33:2 Moses prophesied the Second Coming and again mentioned ten thousands of saints. "And he said, The Lord came from Sinai, and rose up from Seir unto them; he shined forth from mount Paran, and he came with ten thousands of saints: from his right hand [went] a fiery law for them. Related Scripture describes what is going on in heaven prior to the Second Coming: "A fiery stream issued and came forth from before him: thousand thousands ministered unto him, and ten thousand times ten thousand stood before him: the judgment was set, and the books were opened." (Daniel 7:10)
Zechariah chapter 12 addresses the spiritual impact that the Lord's physical return will have on the people. This event will complete the deliverance from the siege of Jerusalem. "I will pour upon.. the inhabitants of Jerusalem, the spirit of grace and of supplications" and it graphically depicts the sorrow that will follow the realization of the Jews that they killed their Messiah.
In Zechariah, chapter 14, "Behold, the day of the Lord cometh, and thy spoil shall be divided in the midst of thee. For I will gather all nations against Jerusalem to battle; and the city shall be taken, and the houses rifled, and the women ravished; and half of the city shall go forth into captivity, and the residue of the people shall not be cut off from the city. Then shall the LORD go forth, and fight against those nations, as when he fought in the day of battle. And his feet shall stand in that day upon the mount of Olives, which [is] before Jerusalem on the east, and the mount of Olives shall cleave in the midst thereof toward the east and toward the west, [and there shall be] a very great valley; and half of the mountain shall remove toward the north, and half of it toward the south. (Zechariah 14:1-4)
The mountain splits three ways to provide a safe place for the remnant which are still alive. Here we get the message who the saints are. They cannot be the Jews because their safety is being provided for during the war of Armageddon. What is left is the Body of Christ, the Church - Jews and Gentiles. It proves that the Church is in heaven and consists indeed of the saints who come back with Him.
"And ye shall flee [to] the valley of the mountains; for the valley of the mountains shall reach unto Azal: yea, ye shall flee, like as ye fled from before the earthquake in the days of Uzziah king of Judah: and the LORD my God shall come, [and] all the saints with thee" (Zechariah 14:5)
Note in Ephesians 2:6 we have past tense which means that we are already in heavenly places in the spirit. "But God, who is rich in mercy, for his great love wherewith he loved us, Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;) And hath raised [us] up together, and made [us] sit together in heavenly[places] in Christ Jesus:" (Ephesians 2:4-6)
The Apostle Paul speaks to the saints and faithful brethren in Christ at Colosse: "When Christ, [who is] our life, shall appear, then shall ye also appear with Him in glory." (Colossians 3:4)
Here it proves that Jesus Christ can change us into His saints. "Who shall change our vile body, that it may be fashioned like unto his glorious body, according to the working whereby he is able even to subdue all things unto himself." (Philippians 3:21)
"Looking for and hasting unto the coming of the day of God, wherein the heavens being on fire shall be dissolved, and the elements shall melt with fervent heat? Nevertheless we, according to his promise, look for new heavens and a new earth, wherein dwelleth righteousness. Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of him in peace, without spot, and blameless." (2 Peter 3:12-14)