The use of words. Religion was used to define the area of beliefs around
God or gods, the metaphysical as opposed to the physical.
Now if this is the meaning of the word religion, then to say all religions are false is to
be an atheist, or to believe there is nothing outside naturalism.
But I think as normal this is a totally subjective use of the term religion.
What is meant is any religion that is different from "their version" is false.
And they would say they are not religious, which in normal language means
their form of ceremonies, teaching, rituals etc are true, while everyone
elses is false.
Now to even use words like this is to be very very arrogant. It determines
they can differentiate definatively their position over others, which is clearly
not the case. They use a religious book the bible as their base authority,
and everything they practise is embedded in christianity.
So to put it simply they are lying and missusing words.
Now people who clearly are doing this, miss the point completely. The use
of language in easily understandable ways communicates, but they would
rather reinterpret words and use them differently which is their common theme.
They claim christianity has peverted or corrupted everything, and their version
of the words is correct, and they are the correct type of christian etc.
It reminds me of muslims and Mohammeds claim of the true faith...