Who knows? Hypothetically speaking if that God planned to torture forever everyone on earth who acknowledged Him then that would be a bad thing. Such a God might even lie about His intentions to fool worthy people into spreading His word.
You are assuming that (a) the God can be trusted and (b) the God is good according to conventional human standards of morality. Neither of these propositions is in evidence.
All hypothetical. I am not saying that this is true of the Christian God, but you cannot demonstrate that my proposition is false.
IF there is a God and that God is reality, regardless of any of our beliefs, would it be a "good thing" or a "bad thing" for all the world to believe in this God?