How to Change Your Religion?
Religion is a belief in and worship of a superhuman controlling power, especially a personal God or god. Article 15 and Article 25 of the constitution granted Freedom of religion in India as a fundamental right. As per the article anyone can change his/her religion, according to their wish. That means you are free to choose any religion. In India every citizen has a liberty to act, speak, expression, thought, belief etc.
Aethism/agnosticsm is not include in this list. If you want to embrace aethism then you become irreligious but not certified with Indian govt. After changing the religion, you need to publish it in the Government Gazette.
Steps for Changing Your Religion
You need to publish a short news in local news paper about the conversion and need a non judicial stamp paper which notarized that you embrace (new religion) & two witness. Then Fill a form which is available at urban ministry of India website. Just Submit it. Here we are given the model of Gazette application form for Changing Your Religion