I had this discussion before:
Acts 21:20- "After hearing this they began to glorify God, and they said to him: “You behold, brother, how many thousands of believers there are among the Jews; and they are all zealous for the Law"
word murias - means a ten thousand; by extension a “myriad” or indefinite number: - ten thousand.
literal translation is "many ten thousands" or "many myriads"
you can compare other scriptures with the same greek word:
Luke 12:1 - "12 In the meantime, when the crowd had gathered together in so many thousands that they were stepping upon one another, he started out by saying first to his disciples: “Watch out for the leaven of the Pharisees, which is hypocrisy"
Acts 19:19 - "Indeed, quite a number of those who practiced magical arts brought their books together and burned them up before everybody. And they calculated together the prices of them and found them worth fifty thousand (pente murias) pieces of silver."
Acts 21:20 - "After hearing this they began to glorify God, and they said to him: “You behold, brother, how many thousands of believers there are among the Jews; and they are all zealous for the Law"
Heb 12:22 = "But YOU have approached a Mount Zion and a city of [the] living God, heavenly Jerusalem, and myriads of angels"
Jude 1:14 - "Yes, the seventh one [in line] from Adam, E′noch, prophesied also regarding them, when he said: “Look! Jehovah came with his holy myriads"
Rev 5:11 - "And I saw, and I heard a voice of many angels around the throne and the living creatures and the elders, and the number of them was myriads of myriads(murias murias) and thousands of thousands"
Rev 9:16 - "16 And the number of the armies of cavalry was two myriads of myriads(duo murias murias) : I heard the number of them."
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From Christian Scriptures it would apper there were more than 144,000 in the first century alone. One can argue that God didn't first pick all 144k but chose them randomly throughout the ages but another good arguement is, where is there a clear teaching that there are two classes of Christians? Why does 144k need to be litereal as WTS teaches? Where is the preaching of paradise in the bible? The preaching was of Christ not paradise! As bible isn't truely clear on 144k topic, one can speculate on a lot of things but when it comes to watchtower and their original teachings, I would doubt anything that they initiate as truth and double and triple check everything they say. As you see even the New World Translation translates "thousands" in various way and is not as consistant as wts claims that their bibe is.