Why Hinduism is still sustain even after many thousand years ? And why Hinduism is very important?

Before talking about religions , I would like to tell every one a very important thing ,any religions never teaches us to correct external world , religions are the way to look inward , religions are made to correct our self,not to correct others .But at current time religions means conflict . Now we are talking about Hinduism , which is oldest way living , and still continue the way it was earlier . It's all because of diversity , let's try to understand a very fundamental thing of any religion ,many religions  follow a single scripture and what ever written in that scripture is applicable for every people belongs to that religion . So any person changed anything in that script ,than every person who belongs to that religion will have to follow that change . But in Hinduism , nothing is predefined, no one forced to follow scriptures written thousand years ago . So even any person changed anything in scripture, it will not make big impact because people follow different tradition in distance of few 100 km of distance , same thing happens when Mughal came to India, they tried to change many thing to make India completly a muslim nation , but they were not able to find root  .So basically in Hinduism their no root , and if you want to cut a tree completly you need to cut root . A very simple example I want to tell you , english people visited all over the world and whereever they stayed, they converted whole community to Christianity . At the same time they stayed in India as well, but they were able to convert a few  people to Christianity , it's just because they where not able to find root of Hinduism. In Hinduism there is no commandment  . you can seek ulimate truth of your life in your own way . And if some one want to know ultimate truth he/she must understand it by himself , it can not be possible by simply reading any script written 1000 years ago , we can take reference from scripture but can not depend upon that scripture. I am not telling ,that Hinduism is the best religion , there are many bad things in in Hinduism , like Superstition . But one good thing is there you can take your own decisions , you have full freedom to find the gods in the way you wish. You can claim to scriptures , if you have valid reasons, no one will kill you for that . Since I belongs to Hinduism , it does not mean i will say only hinduism is the best way to live . We read many things in our colleges and schools , does teachers teaches us same things what was teaches by many teachers 100 years ago ?No , syllabus always changed , because  that 100 years ago things already known to every one , We always invent new things . We invent new things by taking reference of older experiments .we never criticized older things . In the same way we should learn from older scripturs but at the same time we need to accept new changes . In Hinduism you are always free to make any revolutions in religions . Because of This freedom amy great peoples like Gautama Budha , Mahabir originated from Hinduism