Everybody goes to heaven then what is hell for?-2

How did the people found out that they are going to heaven and the other sects or religion is going to burn in hell? So the hell is made for people who do not believe in someone else's criteria of what constitutes good deed in order to go to heaven and what may be a good deed to some person may be a bad deed to some other religion. For example, based on the scripture, the Christians eat pork and drink alcohol and the Muslims don’t. Similarly the Jews don’t observe Christmas. And the Hindus and the Sikhs and the Buddhists and countless other religions don’t believe in Jesus, Moses, Abraham, Noah and other prophets. But they all profess to go to heaven even if nobody has gone there and come back to tell us that if their loved ones are in heaven and not hell. Nowadays hell is emphasized less and less and a feel good atmosphere has been created where everybody will be in harmony in heaven that belongs to a particular religion or sect. Like Hell is for the other kind of people and not us. Well when there is heaven then certainly there is hell and some people are going to end up in hell no matter what the feel good attitude that is being preached says otherwise. So as heaven will be populated by people, then hell as well is populated as this is the concept of Justice that has to prevail otherwise what is hell for then?