Atheist evangelists (street epistemologists) answer me this way:
“Boghossian himself says in his book that the purpose of SE is to help people embrace reason. His thesis, so to speak, is that this will cause people to stop using faith, which he considers an unreasonable epistemology.”
“Boghossian” is Peter Boghossian, author of A Manual for Creating Atheists. He came up with the idea for and name “street epistemology.” Thanks to his book we have answers to questions about the “purpose” of street epistemology.
“This book will teach you how to talk people out of their faith.”
That is the stated purpose of street epistemology. That is helpful to know what atheists are doing as they approach Christians with questions why they believe in God, but it doesn’t explain “why” atheists spend their time doing that. Given that atheists believe this life is all there is, why would they spend any of their limited lifetime to talk with people who believe something they don’t believe. Seems like a waste of the little time they have available to them. So, why do they do it? What do they get from it?