That doesn't follow logically, and I can assure you from personal experience that, in this case, logic does not mislead. If you're not sure of God's existence, how can you be sure of his benevolence?
"Doubting" or "not sure" is not the same as one who denies God's existence (and is fixed in his denial); in the case of that sort of person, I would agree with you.
Do you doubt God’s existence?