Katie Holmes -- I Don't Want Scientology Interrogating Suri

Katie Holmes desperately wanted to save Suri from a form of interrogation practiced by the Church of Scientology that she was steadfastly against ... TMZ has learned.

Sources close to Katie tell TMZ, back in 2005 she had witnessed Tom's other kids participating in a Scientology ritual she found to be troubling ... and feared Tom would drag Suri through the same process.

Ex-Scientologists call the process "sec checking." Here's the way it works. The subject holds electrode handles on a device called an e-meter and is then asked a series of personal questions that help the Church locate "areas of spiritual distress."

Some ex-Scientologists claim the questions include:

-- What has somebody told you not to tell?
-- Have you ever decided you did not like some member of your family?
-- Have you ever bullied a smaller child?
-- Have you ever lied to a teacher?
-- Have you ever done something you were very much ashamed of?
-- Have you ever refused to obey an order from someone you should obey?
-- Have you ever gotten yourself dirty on purpose?

During the process, a person called an "auditor" collects e-meter readings.

Several ex-Scientologists have come out against "sec checking," claiming it's a mild form of psychological terrorism designed, in part, to get children to report on their parents.