The gospel which Paul preached is the gospel by which we are saved. (I Cor.15:2)
Not only do Watchtower Witnesses mess with gospel content, but they also distort the nature of salvation the gospel provides. The nature of biblical salvation is justification.
There are three aspects of spiritual salvation in the New Testament
There is Salvation from:
sins penalty – Ro.6:23, 5:16 - Justification (past, accomplished)
sins power – I Cor.1:30, 6:11, Heb13:12 - Sanctification (progressive process)
sins presence – Ro. 8:30, I Pe. 5:4 - Glorification (future heavenly hope)
I Pe.1:3-4, Col.1:3-5
However, 8.5 million JWs believe a gospel which does not save or justify them. They redefine salvation as survival into the new earth where they can attain justification through 1000 years of obedience. After working all their current lives as Witnesses for this promised potential survival, those JWs who are raised from death will join the rest of unjustified humanity, i.e., adulterers, pimps, fraudsters, witches and warlocks etc. to work along with them for eternal life on earth. If only they hadn't heard the Watchtower gospel, they too could have had fun in this life and got a free pass to the new earth.
Now, here is the gospel truth. All Believers in Christ are Justified
Acts 2: 38-39 38 Peter said to them, "Repent, and each of you be baptized in the name of Jesus Christ for the forgiveness of your sins; and you will receive the gift of the Holy Spirit. "For the promise is for you and your children and for all who are far off, as many as the Lord our God will call to Himself."
Acts 10:43 To him give all the prophets witness, that through his name whosoever believeth in him shall receive remission of sins.
Acts 13:38-39 38 Therefore let it be known to you, men and brothers, that through this one forgiveness of sins is proclaimed to you. 39. And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses.
Romans 1:16 For I am not ashamed of the gospel, for it is the power of God for salvation to everyone who believes, to the Jew first and also to the Greek.
Romans 3:21-26 21 But now God has shown us His righteousness; the law and the prophets tell us about it...God's righteousness comes to all who believe, just by their believing in Jesus Christ. There is no distinction. All have sinned and are without God's glory. They become righteous by a gift of His love, by the ransom Christ Jesus paid to free them. God set Him up publicly to pour out His blood before God to take away sin through faith, to show His righteousness...Now He wanted to show His righteousness, to be righteous Himself and make righteous anyone who believes in Jesus. (Beck)