No. Many millions who lived in centuries past and who weren’t Jehovah’s Witnesses will have an opportunity for salvation. The Bible explains that in God’s promised new world, “
there is going to be a resurrection of both the righteous and the unrighteous.” (Acts 24:15) Additionally, many now living may yet begin to serve God, and they too will gain salvation. In any case, it’s not our job to judge who will or won’t be saved. That assignment rests squarely in Jesus’ hands.—John 5:22, 27.