Here is an atheist Satanist witnessing coming to Christ. [Spirituality & Religion]

A large portion of this is propaganda. The fact is people are actors and they do lie if a group pays them.

https://www.cbsnews.com/news/best-seller-about-journey-to-heaven-pulled/

https://www.churchofsatan.com/myth-anton-lavey-deathbed-conversion-to-christianity/

He couldn't have been a true Satanist.