"It's a pretty big change in one's thought processes"
Not really. If you read the entire article, it's clear that the sort of deity Flew discusses is hardly the sort of deity of Judaism.
Deism and atheism are closely related. Deists just believe in one more deity than atheists do.
In my view, a deity which has no attributes or even sentience, as Flew posits, can hardly be defined as a deity. A mindless force, perhaps, but not a deity.
Flew may be somewhat senile.