Atheists are emotionally stronger than theists

[The Industrial Atheist]

If the OP was correct then you'd think atheists would live longer but they don't. Atheism is bad for your health.

ATHEISTS DIE 4 YEARS YOUNGER

Minority stress

Minority stress describes chronically high levels of stress faced by members of stigmatized minority groups. It may be caused by a number of factors, including poor social support and low socioeconomic status, but the most well understood causes of minority stress are interpersonal prejudice and discrimination. Indeed, numerous scientific studies have shown that minority individuals experience a high degree of prejudice, which causes stress responses (e.g., high blood pressure, anxiety) that accrue over time, eventually leading to poor mental and physical health. Minority stress theory summarizes these scientific studies to explain how difficult social situations lead to chronic stress and poor health among minority individuals. It is an important concept for psychologists and public health officials who seek to understand and reduce minority health disparities.

Wikipedia || Minority stress

By the way, for what it's worth, your logic doesn't follow.  It's possible for atheists to both be emotionally stronger and still live shorter lives.

It would be interesting to see how long atheists live in countries where people aren't as religious, like the UK. I couldn't find anything. Probably because no one there really cares who lives longer.