Religions are classified according to their beliefs in God: Atheism – no God, Monotheism – One God, Polytheism – Many Gods. While most of the popular religions fall into one of the three categories mentioned above, Hinduism is the only religion which can be accurately, yet not fully described individually, by all these terms: Hinduism is Atheist at the same time as it is Polytheist at the same time as it is Monotheist, as well as henotheistic, i.e. belief in one major God with other subsidiary Gods “worshippable” too! Oh, and Hinduism can also be considered “monist” i.e. the belief that all the seemingly disparate elements in this universe can be reduced to one single unity. So there you have it: Hinduism is perhaps the only religion in the world to which all kinds of epithets such as above apply, and yet fall short of suitably encompassing its definition! That’s what a living history of 4000 years does to a religion I suppose!
There are a sect called Carvaka (Wiki it!), who simply put “don’t care whether God exists or not”. They are indifferent to the phenomenon! Among the extremely well evolved ancient Hindu philosophical schools of thought (almost to the point of fatigue), there are two more philosophical schools of thought, namely Mimamsa and Samkhya which likewise maintain a healthy tradition of philosophical skepticism albeit not going as far as terming themselves atheists like the Charvakas. This was not a one-off thing!!
A healthy argumentative tradition has been the defining point of Hinduism even from its early days, when its prime scripture, the Rig Veda was written.
Look at this hymn on the origin of creation:
Who really knows? Who will here proclaim it?
Whence was it produced? Whence is this creation?
The Gods came afterwards, with the creation of this universe.
Who then knows whence it has arisen?
Whence this creation has arisen
– perhaps it formed itself, or perhaps it did not –
the One who looks down on it,
in the highest heaven, only He knows
or perhaps even He does not know.
– Nasadiya Shloka, Rig Veda c.1700 – 1100 BC
Pause for a moment and consider this: in this day and age, when “blasphemy” is taking lives by the hundreds everyday, a religion incorporated atheism and a healthy tradition of scepticism in ancient days itself, making it a part of its ethos and tolerating it ever since!