How can people be actually converted?

Have you ever convinced a religious person to become atheistic? How did you do this? How long did it take? Were the people in some sort of life crisis, or were they just living along?

This is probably a quite difficult task of persuasion. So stories how people were successful at it could be very interesting to improve ones’ persuasion abilities.

Relatedly, it might be interesting to know what religious groups have gathered on techniques to convert people to their religion—are there some manuals/​techniques floating around?