I was a JW for most of my life. I'm now in my mid-40s. I served as an elder in the congregation. I was very much a believer. Until I started researching. Not just a couple of weeks of researching. Over two very intense years' worth. It tapered off since then. That was almost five years ago and my research still continues. I have come to the very opposite conclusion.
Luke 21:8 has already been brought out here, so I won't discuss it.
You said you believe JWs are right because they preach the good news. The question is: what "good news"? The good news JWs preach is that God's kingdom will come and destroy the wicked and set up a theocratic government, and that people will live in a paradise earth.
Gal 1:6-9 says: "I am amazed that you are so quickly turning away from the One who called you with Christ’s undeserved kindness to another sort of good news. 7 Not that there is another good news; but there are certain ones who are causing you trouble and wanting to distort the good news about the Christ. 8 However, even if we or an angel out of heaven were to declare to you as good news something beyond the good news we declared to you, let him be accursed. 9 As we have said before, I now say again, Whoever is declaring to you as good news something beyond what you accepted, let him be accursed."
What was the good news Paul and others preached?
Acts 13:32-41: “So we are declaring to you the good news about the promise made to the forefathers. 33 God has completely fulfilled it to us, their children, by resurrecting Jesus; just as it is written in the second psalm: ‘You are my son; today I have become your father.’ 34 And the fact that He resurrected him from the dead never again to return to corruption, He has stated in this way: ‘I will give you the expressions of loyal love promised to David, which are faithful.’ 35 So it also says in another psalm: ‘You will not allow your loyal one to see corruption.’ 36 David, on the one hand, rendered service to God in his own generation, fell asleep in death, was laid with his forefathers, and did see corruption. 37 On the other hand, the one whom God raised up did not see corruption.
38 “Let it therefore be known to you, brothers, that through this one a forgiveness of sins is being proclaimed to you, 39 and that from all the things from which you could not be declared guiltless by means of the Law of Moses, everyone who believes is declared guiltless by means of this one. 40 Therefore, watch out that what is said in the Prophets does not come upon you: 41 ‘Look at it, you scorners, and be amazed, and perish, for I am doing a work in your days, a work that you will never believe even if anyone relates it to you in detail.’”
What of "paradise earth"?
1 Cor 2:9,10: "But just as it is written: “Eye has not seen and ear has not heard, nor have there been conceived in the heart of man the things that God has prepared for those who love him.” 10 For it is to us God has revealed them through his spirit, for the spirit searches into all things, even the deep things of God."
God HAS REVEALED the things he has prepared. To whom? Paul said, "to us". Why is it that Paul NEVER spoke of a paradise earth? Where did this come from? Is it "another sort of good news"? According to Galatians, one who teaches "another sort of good news" regardless of the source, be it a human or an angel, should be accursed.
Believer, you can believe what you want to. As for me, I've already done so, and continue to do so. Most JWs are nice people and are sincere in their beliefs, just as I am sincere in my beliefs. JWs are like any other religion out there... claiming to be the true religion. But, as they have admitted quite openly, their leaders, the Governing Body, is not infallible nor inspired and can err in doctrine. Why in the world would we want to follow anyone who tells us they could actually be wrong?