Certainty of attack

Peace and blessings.
For a long time (about three years) I have been trying to understand and present to myself and others some kind of barrier that puts my life in constant turmoil.
I hope that in the following lines I will be able to lay out my thoughts as clearly as possible. And perhaps this is the place to apologize for the slightly convoluted style of things. It takes great genius and talent to recognize the form of the content stored within the recesses of the soul in a conscious and conscious manner and from there translate it into words and sentences. A talent that I apparently lack, so I apologize.
Well-
I don't understand where my rabbis derive this certainty in the righteousness of our ways (in general and their ways in particular)?
More than once I have attended a lesson given to us in a yeshiva in which content was spoken that truly uplifted the soul, instilled in my heart certainty in our faith and sowed in it a joy that comes from the resolution of doubts, but at the same time that these pleasant feelings were emerging from within me and for just a brief moment I was able to savor the general feeling of stability that was afflicting my soul, I saw in my imagination a gathering of extreme left-wing organizations (as an example) from which its members and supporters derive the greatest comfort and identification, a flourishing sense of certainty and a strengthening of the attitude existing in their souls towards those who disagree with them while the reservoirs of eagerness and determination to realize their vision of the end of days become overflowing.
If the truth is one, then how come there are disagreements in the world? Why does everyone recognize a different truth?
And so it is, from where do we derive our certainty in the righteousness of our ways? By what right do we judge everyone to be a liar and our attitude towards them to be critical and demanding?
And if we prove to ourselves with reason – and indeed our reason, as much as any human mind, operates from the fabric of our entire life – then it is certain that it will be said of our method (and of others of their method) that it is the correct one.
What value is there in this feeling of certainty in our hearts if we, like everyone else, say that the truth is embraced in our arms?
This criticism, of course, is not directed only at us, but at anyone who stands up and speaks out on any subject or matter.
What bothers me is the real fact that it is very likely that if I had been born into a family living several hundred kilometers from my area, whose people are currently rioting on the fence and harming my country, my entire structure of thinking about the world and its details would have been completely different, and that everything I say about it today, which is true, I would have condemned and condemned, and certainly destroyed.
When I hear my elders speak and try to mold my soul to look at the world in a certain way, I am trapped inside and unable to receive Torah and love of Israel from them because I tell myself that it is clear that this is how he thinks, since he was raised to speak and think in this way.
If everything is subjective, the postmodern thinkers are right, who believe that everything is legitimate, and that anyone who tries to demand the truth in our lives, if they are honest enough and sharp enough, simply won't be able to say a word. Or think any thoughts at all.
Certainly, one cannot lead a life like this, and indeed it seems that today's culture is no longer interested in truth and absolutes, but rather that everyone should do whatever is right in their own eyes.
But from my current state of mind – I am filled with silence. I really cannot utter a word. I really cannot know what is true and what is fiction. And just because I cannot live like this does not mean that it is not true. (I am aware of the internal contradiction that screams from these words – if I say that the truth is that I cannot find out what the truth is, I have thereby contradicted the beginning of my words. And from here the loop will continue ad infinitum).
As I'm sure you can tell from the tone of things here – I'm very confused and troubled. In fact, the truth is that I'm not alive. I'm standing still and slowly sinking. Please help me understand. Thank you very much.