If they're Jehovah's Witnesses, try "I don't accept the Bible as the direct word of God".

On the other hand, if you're interested in the Bible as a historical document, you might invite them in once they understand that you don't accept it (just to be fair).

The JW 'church' has done an amazing job of going to as many original sources as possible and verifying / re-translating into modern languages. Their belief system is based on careful parsing of original text, so that phrase above will make it clear you're 'lost' - but if you've any interest in that period you might find a conversation fascinating.

Sadly, I have no phrase that might work on Evangelicals. I have relatives down South who are - and they can't understand why someone who's familiar with the NT doesn't care to be 'saved'. Kind of painful as they're dear people.

Apologies for a serious reply to an amusing article.