You can state what you believe. No problem.
You can say why you believe what you believe. No problem.
But to put words in another Freeper's mouth - whether what he believes or why he believes it - is mind reading, attributing motive, making it personal and incites flame wars.
For instance, it would incite a flame war for an RF poster to say "You believe Mary is God" or "You hate Mormonism because you believe that website" or "You say that is blasphemy because you don't know any better" and so on.
Equivalent points can be made without making it personal, e.g. "It appears to me that those statements elevate Mary to godhood." or "That website mongers hatred towards Mormonism" or "Those of us who embrace that doctrine do not call it blasphemy as you just did."
If someone writes. “Mary is God” then how do they not believe “Mary is God”? I understand if I write “Mary is venerated by the Catholic Church” and the response is “You believe Mary is God.” Because that is indeed an inference based on what I believe is the implication they made in their post.
Belief does not just mean what a person thinks. It also means having a strong opinion about something. In matters of faith it is a statement of what a person accepts as doctrine and therefore true.
Me: “I believe in God the Father almighty.”
Response “You believe in God the Father.”
The above is a simple statement affirming what another has already stated.
Me “Mary remained a Virgin.”
Response. “You write that because don’t believe in the Bible.”
This is an example of attributing motive.
The word believe is used to mean different things in the contexts above. If there is another word that expresses a statement is grounded in one’s doctrine please let me know and I will use that.
The truly ironic thing is that by saying it was what Dr. E believed I was trying to show that I could respect a view that arose from that factor. Even if I disagree with it.