"Religion" as a polluted word

What does it mean for words like "religion" to become "polluted"? How does it happen, and can they be cleaned up and made usable again?

Watts, Galen, and Sam Reimer. “Symbolic Pollution and Religious Change: The Religious Imaginary of Anglo-Canadian Spiritual but Not Religious Millennials.” Sociology of Religion, June 9, 2024, srae012. 

https://doi.org/10.1093/socrel/srae012.

 

https://academic.oup.com/socrel/advance-article/doi/10.1093/socrel/srae012/7690204