They criticise everybody else's religion on the grounds of what the menbers do who are not faithful.What's good for the goose...
You miss the point.
The point is that Jehovah puts before his people the choice to choose life or choose malediction.
That choice is not put before those who are not his people. Although they can choose life rather than malediction but choosing
to become one of Jehovah's people, but until then there is no choice.
We criticize other religions not because some are unfaithful, we criticize them because they choose the malediction. Or because their lack of choice to be on God's side places them in malediction.
Also because if the whole number of these "everbody else's religions" would as a whole do God's will there would be these wars and reports of wars, etc.