Why do people have to change their religion ?

I do agree with you. I feel first of all what is the need to change and if you do change then don't shift from that at all whole of your life. Anyways, try to just values every other persons views about their religion teachings and followings and just don't point out saying these are flaws in your religion, every one should not just have respect for their religion but also tend to respect other religions too. Just stay calm rather than even commenting.