Is Hinduism a religion or a way of life?

Hinduism is definitely a religion.

To put forth my point we will have to first define what is religion and way of life (lifestyle).

In layman terms:
Religion is one’s faith in an unknown power and the practices associated with it. In reality, be it a Hindu, Christian or Muslim, who believes in God or an Atheist who believes in no God, cannot prove the logic behind their faith.

Way of life (lifestyle) is the way we carry out our day to day activities based on the traditions and culture where we live.

To elaborate:
American lifestyle: America is a predominantly Christian country. We refer to the lifestyle of people living in the US as an American lifestyle and not as a Christian lifestyle.   
Middle Eastern/ Arabic lifestyle: Though majority of people living in Middle East practice Islam but, we refer to them as following a Middle Eastern/ Arabic lifestyle.    
Japanese lifestyle: Japanese follow two religions mainly Shintoism and Buddhism. We refer to their lifestyle as Japanese lifestyle. 
Indian lifestyle/ Hindu lifestyle: Majority of people living in India are Hindus but we must refer to the lifestyle as Indian lifestyle and not as Hindu lifestyle or Hindu way of living.                                      

To discuss the perspective further, let’s consider the argument by critics that there was a way of life in the Indian subcontinent centuries back. It didn’t even have a name until the birth of any other religion in the world. Pushing this argument people say that anyone living in India is a Hindu and has a Hindu way of living. Let us delve a little deeper.

If that is the case,
– A Christian who lives in India and believes in a Christian God, is also a Hindu and has a Hindu way of living?
– A Muslim who lives in India and believes in a Muslim God, is also a Hindu and has a Hindu way of living?
– A Hindu who lives in India and believes in a Hindu God, is also a Hindu and has a Hindu way of living?
– An Atheist who lives in India and believes in no God, is also a Hindu and has a Hindu way of living?

Let us draw a parallel here. Before the invention of mobile phones, people used to ask us for our phone number. Now, with the invention of cell phones on being asked the phone number, we specifically mention the landline or mobile number. The term phone number has lost its relevance. 

Similarly, with the spread of multiple religions, calling everyone living in India, a Hindu has lost its relevance. An Indian who believes in a Christian God is a Christian, an Indian who believes in a Muslim God is a Muslim and an Indian who believes in a Hindu God is a Hindu and an Indian who believes in no God is an Atheist. These are all distinct religions including Atheism.

Now let’s consider the Hindus living in India. The only common thing among Hindus across India are their belief in the:
– Hindu Gods
– Hindu scriptures

In reality, Hindus living in South, North, East and West have completely different ways of living. In North you can touch the deities in temples whereas in South you can’t. In East, some Brahmins eat fish but everywhere else they are vegetarians.

The only common lifestyle we all share is an Indian lifestyle or way of living and not a Hindu lifestyle and Hindu way of living.

To sum it up, anybody living in India be it a Christian, Muslim, Hindu or an Atheist is an Indian and follows an Indian way of living (lifestyle) and not a Hindu way of living.