Responding directly to what you wrote is not inferring anything.
I don't know why you find it so incredulous that a religious writer might not believe in what they were writing. Do you think the likes of L Ron Hubbard or Joseph Smith believed what they were writing was true?
I didn't and don't say all religious writers don't believe what they're writing. You said/implied all religious writers do believe in what they're writing . . .
Whether I think you believe in what you wrote is not determined by what I think. If that is the case I think you believe you are God. If you say no, you are lying.
What you believe depends on what you actually believe. Now of course you could be lying and if that is so, then I must give evidence for that.
The same applies to you: Someone is not lying just because you say so!!!
So I don't think you are lying. I think you are mistaken in that it is not a fact that one other humans simply believe something or are lying, if you say so.
So do all religious writers believe in what they write?
If they believe, they are religious. So a person, who deceives about the religious beliefs, can't be religious, because a religious person believes.
If they deceive, they believe it is for a higher purpose; i.e. a religious belief.
If they deceive for another purpose, they are not religious.
Religious persons believe.
Con artists deceive.
No all religious persons are con artists otherwise.
We even have a name for a sub-group of con artists - honest con man. But that means that the con man believes in the con. So if an honest con man believes "the con" about religion, it is a religious belief and thus not really a con.
So yes, all religious writers believe, otherwise they won't be religious. So it is upon you to show that L Ron Hubbard or Joseph Smith were not religious. I.e. not religious means that they are something else and that something else is a positive claim for which you have to show evidence and not just think.
You really aren't that good at evidence, it would seem.