This is pretty ironic - and very silly.
The JW's DO NOT preach the Gospel that the first century Christians preached, which Jesus said would be preached, unchanged, right up until the 'End'. JW's have created a very different Gospel. But Paul said:
"I am astonished that you are so quickly deserting the one who called you by the grace of Christ and are turning to a different gospel— which is really no gospel at all. Evidently some people are throwing you into confusion and are trying to pervert the gospel of Christ. But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let him be eternally condemned! As we have already said, so now I say again: If anybody is preaching to you a gospel other than what you accepted, let him be eternally condemned!" - Gal 1:6-9.
So what were the 1st C. Christians preaching? What was their good news? That by becoming Christian you could be a brother of Christ and have a heavenly hope. That was the Christians Gospel. That was the hope for ALL TRUE CHRISTIANS. No other hope for CHRISTIANS was offered in the NT. And this message - no other- was the one to be preached right until the end.
"By this Gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain." - 1 Cor 15:2.
"And if anyone does not have the Spirit of Christ, he does not belong to Christ.... because those who are led by the Spirit of God are sons of God. For you did not receive a spirit that makes you a slave again to fear, but you received the Spirit of sonship. ... Now if we are children, then we are heirs—heirs of God and co-heirs with Christ, if indeed we share in his sufferings in order that we may also share in his glory." - Romans 8.
So, if you are not "anointed" you are not Christian - "does not belong to Christ". Of course, Paul and the other apostles and NT writers never once preached a message about Christians living on a paradise earth. Never. So, by perverting the Gospel, and preaching "another gospel" and by making 'mutant (so-called) Christians' WITHOUT a heavenly hope - something which is never mentioned in the Bible - JW's have adulterated the Christian message and are, according to the Bible, "accursed".
How ironic then that they who have probably deviated from the Gospel most, should boast that they are the only ones preaching it and attack other Christians - or "beat their brothers" - because they don't follow the error of JW's.
"Truly, truly, I say to you, unless a grain of wheat falls into the earth and dies, it remains alone; but if it dies, it bears much fruit. He who loves his life loses it, and he who hates his life in this world will keep it to life eternal. If anyone serves Me, he must follow Me; and where I am, there My servant will be also; if anyone serves Me, the Father will honor him". (John 12: 24-26)
"Do not let your heart be troubled; believe in God, believe also in Me. In My Father's house are many dwelling places; if it were not so, I would have told you; for I go to prepare a place for you. If I go and prepare a place for you, I will come again and receive you to Myself, that where I am, there you may be also. And you know the way where I am going. Thomas said to Him, "Lord, we do not know where You are going, how do we know the way?" Jesus said to him, "I am the way, and the truth, and the life; no one comes to the Father but through Me." (John 14:1-6)
"It is a trustworthy statement: For if we died with Him, we will also live with Him; If we endure, we will also reign with Him... " (2 Timothy 2:11-12)
"So then, brethren, we are under obligation, not to the flesh, to live according to the flesh-- for if you are living according to the flesh, you must die; but if by the Spirit you are putting to death the deeds of the body, you will live. For all who are being led by the Spirit of God, these are sons of God . For you have not received a spirit of slavery leading to fear again, but you have received a spirit of adoption as sons by which we cry out, "Abba! Father! " The Spirit Himself testifies with our spirit that we are children of God, and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him so that we may also be glorified with Him". (Romans 8:12-17)