High doubt on Buddhist teaching I hope you can clarify my doubts:


If one is skeptical concerning enlightenment (because no one besides the Buddha and mysteriously only those people in his time got enlightened) does it then even makes sense to practice Buddhism? The whole point is to escape impermanence and attain the unconditioned, Nirvana. If monks like Bhikkhu Bodhi even claim not to have realized enlightenment how are lay people going to realize this?
I agree on the whole point concerning anicca, but impermanence is always used in a bitter way. Yes, we are going to get sick, old and then die at the end. Yes we cant cling to experience, but we can recall positive experiences and they change our brain.. this is why loving kindness works. Impermanence is always exploited to the extreme.. "well since everything is impermanent I give up on everything and better become a monk." Isn't that true? If you go by that belief it's quite bitter because monks that are long in their business haven't already realized nirvana/awakening and the chances are high that they wont. So why then belief in Nirvana and Enlightenment?
Couldn't it be the case that Buddhism is just another fairy tale that want's to trick people, to live poorly and to keep quiet in tough times due to getting bad karma otherwise?
If enlightenment is just about grasping the 3 characteristics and experiencing them during meditation then even an "evil" person can become enlightenment 
Why does it take so long to become enlightenment if it is just about seeing the 3 characteristics?
What if rebirth truly doesn't exist? The whole point in striving for enlightenment is then pointless.
Most people and monks don't question every doctrine. They use it as Thanissaro Bhikkhu said as a "working hypothesis" and therefore filter out any contrary evidence. What I mean by this is that they are succumbed to an argument of authority.
Good honest question, love it. Let me give you an honest answer.


  
  If one is skeptical concerning Enlightenment (because no one besides the Buddha and mysteriously ONLY those people in his time got enlightened) does it then even makes sense to practise Buddhism?
  


Enlightenment is attained by a lot more people than you realize. It's just not advertised for reasons of political correctness and compassion. It's like telling kids there is no Santa Claus - kinda pointless and only hurts the kids.


  The whole point is to escape impermanence and attain the unconditioned, Nirvana. If monks like Bhikkhu Bodhi even claim not to have realized enlightenment how are lay people going to realize this?


This is not how it works. You don't literally "escape impermanence", instead your perception of reality changes in such a way when impermanence no longer matters. Enlightenment is not becoming a Superman. It's more like getting able to see the true nature of "The Matrix". Again, this is not a literal change in how you see stuff, it is a fundamental change of one's mental framework and therefore of one's interpretation. 


  2 I agree on the whole point concerning anicca, but impermanence is always used in a bitter way. Yes, we are going to get sick, old and then die at the end. Yes we can't cling to experience, but we can recall positive experiences and they change our brain.. this is why loving kindness works. Impermanence is always exploited to the extreme.. "well since everything is impermanent I give up on everything and better become a monk." Isn't that true? If you go by that belief it's quite bitter because monks that are long in their business haven't already realized Nirvana/Awakening and the chances are high that they won't. So why then believe in Nirvana and Enlightenment?


This seems to be a misunderstanding of the attitude of detachment/revulsion, promoted by Theravada and the lower yanas of Mahayana for the sake of motivating beginners. Accepting Impermanence is not all there is to [Mahayana] Buddhism, far from it. It's more about seeing how things truly work and learning to work with them.


  Couldn't it be the case that Buddhism is just another fairy tale meant to trick people who live poorly to keep quiet in the tough times through fear of getting bad karma otherwise?


There is an element of fairy tale in Buddhism, and there is a real element. And the real element is pretty damn real and mindblowing.


  If Enlightenment is just about grasping the 3 characteristics and experiencing them during meditation then even an "evil" person can become enlightened.


It's much more than that, both in the sense of intellectual realization, and in terms of actual personal mastery in real life.


  Why does it take so long to become Enlightened if it is just about seeing the 3 characteristics?


It takes a long time because we have some deeply lying conceptual mistakes about reality, due to which we have accumulated much emotional baggage rooted in those conceptual mistakes, and on top of that we tend to actively fight it when anyone tries to show us our mistakes and delusions. We have all these explanations and rationalizations that we cling to, and they are connected with events in our personal lives, providing support and sustenance to delusion. It's like a tangle of hair made from wrong concepts, emotions, and karma - very difficult to untangle.


  What if rebirth truly doesn't exist? The whole point in striving for Enlightenment is then pointless.


Rebirth of individuals does not exist. There is rebirth of information. Because future lives are made from information left by the past lives, Enlightenment is not pointless.


  Most people and monks don't question every doctrine. They use it as Thanissaro Bhikkhu said as a "working hypothesis" and therefore filter out any contrary evidence. What I mean by this is that they are succumbed to an argument of authority.


That is true. Most people are unfortunately pretty closed-minded - not because of a fault of their own or inherent weakness, but (quite counter-intuitively!) out of their best intents. People try to make sense of it all using their logic and common sense, and filter out all nonsense. But because it is so tangled up, it is not always obvious what is nonsense and what is real. Deferring to authority is infinitely easier than trying to make sense of it all by oneself. 



Unfortunately this entire Buddhism thing is a mess. It has this extraordinarily valid and useful stuff in its core, lots of confusion around that, and even more fairy tale stuff on the outside. I was very confused by it for decades and suffered a great deal. Now that I got it, the purpose of my life is to help people avoid wandering in the jungle as I did, and go straight to the well. Sometimes when doing this I wonder if by my efforts I only contribute to the jungle, as did my predecessors before me. But alas, I do what I can :))))

Let us know if we can help you here and please don't hesitate to start asking specific questions about Buddhist concepts and their application to real life.