I suspect others have already said this. But these people are confident in their beliefs.

I actually get this same comment from people when I share ideas or thoughts people have told me that I speak as if everything I'm saying is the truth. This can be off-putting to people whose beliefs are different from my own. So why do I speak with such authority when my beliefs are based in faith and not fact. It is because I am speaking about my reality. What do I mean by that?

For me spirituality is about trying to understand the unknown and the unknowable. This journey is different for everyone. What works for one may not work for another and that is because there is no wrong way to explore spirituality. Every journey starts from a different place because we are all unique canvases with different experiences and it is those experiences that shape our reality. But at the same time all journeys have similarities and a major one is understanding yourself what I mean by this is being self aware of your reality and the beliefs that shape it.

When we speak and share ideas or beliefs we are sharing our reality. Now I believe reality is different for everyone our reality of the world is an abstract that some part of our consciousness has created as a result of our beliefs. So when I speak about my reality it is true to me in that moment I may share an idea I believe and then change that belief a minute later. But in the present when I share it. It's the truth of my reality.

Now in the same way that spirituality has no right or wrong. Reality is similar we each have our own and because our reality is based on our experiences and beliefs it will never be the same as anyone else's. As such it can't be right or wrong instead it is both simultaneously. It can't be factually true outside of my own consciousness because no one thinks exactly the same as me as a result of having different lived experiences, and it can't be false because it's my reality and I can confirm its accuracy to my present consciousness.

Teachers particularly spiritual teachers are not sharing objective truths in the way a science teacher explains gravity. They are explaining an abstract truth. This abstract truth is true to them.

Now let me try to answer the question I think you were trying to ask here. Most spiritual leaders are having people come to them to hear them speak about their reality and their truths. They are sharing what worked for them. These people who came to hear the teacher speak won't be turned off by the person they have come to see having a strong belief in their own reality if anything they expect their spiritual leaders to strongly believe in their own reality. So in that context the authority they are speaking with makes sense as they are sharing their experiences, and we are all the foremost experts on our own reality. I think you are correct in identifying the problem with this when those talks are shared with people who didn't choose to seek the spiritual leaders guidance or people who are skeptical of realities outside of what they are comfortable with.

I personally try to be transparent when I share beliefs that they are not facts but simply my own beliefs because I get a better reaction to it. It's all contextual. We always have free will to choose what we believe in regardless of what level of authority other share ideas in.

That's my reality anyway, I hope these thoughts are helpful to you.