A deep adhesion to atheism does not mean a confident attachment to the theory of atheism, but the inner certainty that there is no god. Thereafter, such an inner certainty shapes someone’s entire personality.
The true religious believers shape their personality, too, but in the name of their faith. And this is the main reason for which they cannot be persuaded to renounce to their faith, in spite of all the rational proofs.
Nonetheless, the true atheists cannot change their personality. Though, we find that some of them accepted religious conversions. And the actual atheists are many times rebuked by the religious believers with the presupposition that they will finally renounce to their godless creed, especially when they will be nearly their death.
But such conversions are almost always false transformations. They are in fact the ways by which atheist personalities express themselves in religious terms. Since the main advantages to be gained from atheism are a strong sense of freedom and a pronounced individuality, it can be followed how the converted atheists are bent on exaggerating the religious devotion, such exaggeration or bigotry being a manner to express the force of a free personality in a religious frame.
There would be worth studying how many founders of religions are not in fact only converted atheists.