Interestingly a world that cannot lie is a world without religion.
I see a lot of threads complaining about people being 'asshurt' (elegant turn of phrase) about movies that make fun of religion, or the protagonist's idea of life after death involving concepts similar to popular ideas of what 'heaven' is.
Both are wrong: this film does not mock religion, it mocks people's understanding. If you think 'heaven' involves everyone having their own mansion then you, my friend, are an idiot.
What is curious though is that a world without lies has no religion in it at all. Do Ricky Gervais and Matthew Robinson consider belief to be the same thing as knowledge? What are the implications of this? In what context can statements be made? What does 'true' mean - is it a priori, as the film makers seem to believe?
The reality is that the film is a bit of a mess, philosophically speaking. What we are left with is a funny idea explored in a bit of a rush in a film which needed a few re-writes before release.