This is a common prevarication. It is a matter of long standing common law, that

This is a common prevarication. It is a matter of long standing common law, that it does not matter what you intend, it matters onlly whether you have performed sufficient due diligence to promise a truth claim.
Since you cannot perform due diligence on claims, and you choose to anyway, while this is common, it is still deception and a tort (crime)
You could say you have faith in such a thing, you can say you believe in such a thing, your could say you have confidence in such a thing, but you may not claim it is true.
The reason being
(a) you may be ignorant (honest) but irresponsible (b) you may have biases or agendas or commitments and again irresponsible for failure of self regulation, or (c) you may intentionally act irresponsibly. But you are not the judge of whether you commit a crime and whether your intent matters. Instead, we look for motive. You have a motive for (a) claiming truth that which is not testifiable, (b) a motive for doing so (c) even if that motive is petty and the consequences merely a common harm to the informational commons (others). (d) and forcing others (like me) to defend the commons from your irresponsibility.

Reply addressees: @repairmanscully @martinmbauer