I didn't find the arguments given in this essay convincing enough to justify atheism. To me the reason of his atheism was not his vanity, rather, it was his hate against God for creating a world full of inequality.
Many arguments made by Bhagat Singh Ji was based on certain refutable assumptions of how and why theists believe in God. Not everyone believes in God and Religion the way he assumes. In fact, the meaning of religion has been widely accepted to be varying according to one's own perception of it.
Moreover, what I found to be one probable benefit of being an atheist, as he points out, is later impliedly refuted by him.
Also, I don't think he has accurately addressed the arguments of theists vis-a-vis science.