This post is really a summary of points made in various other posts. I have put it together becaus this is a question I often see asked in various forums. Also, it has been a while since I published anything, as I have been rather busy recently. This is also a question to which you will see several different answers, and I think it is useful to put them together in one post.
Some people say “No”.
There are a few people who say that you should never convert; whatever religion you are born into should be yours for life. I think that this is incorrect, if you have a strong feeling towards a religion and you feel that the religion you are born into is not for you then follow the path that you feel guided on. Hindus believe that people can be guided by gurus that are not physically present (see my post “Books, Leaves and Gurus“). If you are convinced that a path is right for you, and have seen signs that it is right then don’t worry about this argument. This argument also does not take into account people brought up with patently wrong beliefs; should the children that survived the Waco seige continue to follow the teachings of David Koresh?
I have had nothing but support from Hindus I have met, I have only read this point of view on a few blogs. I would not worry about conversion being opposed. As mentioned later there are many Hindu schools that openly accept conversion and have a process of accepting new membes.
Some say that “Hindu” does not refer to a Religion.
Some people may quibble that Hindu refers to origin (People beyond the river Indus) rather than belief. They say that you can follow Sanatana Dharma (The eternal way) but this will not make you a Hindu any more than if you joining the Greek Orthodox Church would make you Greek. To me this is just word play, many words have changed from their original meaning and certainly in English the word “Hindu” is used to refer to belief. If someone insists that you can only be a follower of Sanatana Dharma and not a Hindu I don’t think it is worth arguing over, it is only a word and what is important is belief and practice.
Some say “Just say you are a Hindu and you are”.
Other people say that you don’t have to convert, just follow Sanatana Dharma. All you have to do to become a Hindu is to follow the principles of Hinduism. If that is sufficient for you then fine. I certainly would not argue with anyone claiming to be a Hindu who held Hindu beliefs and followed the practices.
Some say “Become a Hindu Indirectly”.
Another answer that you might get is that becoming a Hindu is analogous to becoming a European citizen. You cannot become a European citizen directly, but by becoming a citizen of one of the European countries you are automatically a European citizen. Similarly there is no process or admission into “Hinduism”, but there are many Hindu Sampradayas, organisations, and traditions that do have processes of admission. By joining one of these one becomes not only a member of the particular tradition but also become a Hindu. Personally I think this is better than the “self declared” route, because the tradition will assist you in learning and following practices.
I would recommend the book “How to become a (better) Hindu” available online or to buy. This book takes the third point of view and describes the various Hindu schools and their beliefs.