This is a very good article which lays out detailed, factual reasons why one cannot be both a Christian and a Scientologist.
https://scientologymoneyproject.com/2018/05/30/why-you-cant-be-a-christian-and-a-scientologist/
https://scientologymoneyproject.com/2018/05/30/why-you-cant-be-a-christian-and-a-scientologist/