Russia’s Supreme Court seems to think so.
They ruled that the group's St. Petersburg headquarters and 395 churches could be seized and liquidated. All church activities, including worship and door-to-door evangelizing, were banned. Those who defy the ruling face a fine of several thousand dollars and six to 10 years in prison.
Of course, this won’t purge Russia of the Watchtower Bible and Tract Society. History shows that when you try to ban a religion, all you do is drive it underground. Meanwhile, the Jaydubs have a PR opportunity you can bet they’ll exploit. They can call the court’s decision persecution (they’d have a point) and offer it as a sign that they have the truth (they wouldn’t have a point). They might cite Matthew 5:11-12:
Blessed are ye, when men shall revile you, and persecute you, and shall say all manner of evil against you falsely, for my sake. Rejoice, and be exceeding glad: for great is your reward in heaven: for so persecuted they the prophets which were before you.
Are they harmful? You could make a strong argument that filling minds with nonsense is harmful. But then you’d have to ban every religion, not just the Jaydubs, and that brings us back to the troublesome fact that banning religion only drives it underground, often strengthening adherents’ resolve.
A better solution might be to get religion out of public education while stepping up instruction in science and critical thinking. Just a thought.