I think the problem here is: how far can you divert from the "real" Christianity and still be considered "saved"?
It is all stories in a book. Stories that are there for a reason. Stories that some - quite a lot of, in fact - people think are "literally the Word of God". Not something humans told... but the revelations of a divine, infallible beings.
So where do you draw the line what you "need" to accept, and what not? If someone believes that the resurrection of Jesus was not "factual", but a "metaphorical truth"... would that be so different from a "factual" in contrast to a "metaphorical" floods?
If someone told you that, if there are "untrue" stories in the Bible, you could not accept as fact any of them... how would you counter that position?
If someone insists that you need to take every single word in the texts "literally" (and in the way they think it is meant), and their weird and often demonstrably false claims cause unbelievers to reject Christianity... how would you defend the "truth" in this case.
Of course you can sit back and declare that this isn't your problem, because you believe something different... but then: whose problem is it?
First off, there are things you can divert from and still be considered saved. There is a bare minimum requirement for salvation to be considered a Christian.
No one has all knowledge overnight, we all as Christians are in varying stages of learning, so some are more knowledgeable than others, and some just haven't gotten there yet in their understanding and this must all be taken into consideration.
Bare minimum belief for salvation is seen in the thief on the cross, and spelled out in the Bible otherwise. We must believe in our heart in Jesus in truth; (in His Life, Death, and Resurrection) followed by confessing with our tongue His Lordship..
That's it... if you honestly believe those things and acknowledge He is Lord over you, you are officially a baby in Christ.
You don't have to believe anything else for salvation.
Yet, most people don't get to that point of belief in a bubble, there is usually much examination to get to belief.
First, to believe Jesus was a living being whom people claimed was the Messiah of the Jews, who was killed by Romans by crucifixion yet three days after death rose bodily from the dead, you'd likely also believe the biblical accounts, and give much credence to the Bible having basis in fact.
Which of course, usually means you can't believe the new testament to be a fictional story book and still be saved..
Yet - it doesn't mean its necessary to salvation to have ever even read the Bible..or believe in the Bible itself. It's not scripture we need faith in, in the end, it's the person of Jesus.
Therefore if an Angel of God comes to someone and tells them Jesus is real, is the Messiah who lived, was killed via Roman crucifixion, and rose bodily from the grave 3 days later, then they may have come to faith outside of biblical evidence and need to do some catch up on canon..
There is a learning curve for all of us, and a bare minimum requirement to belief and salvation and what our understanding is when we get to a saving knowledge of Christ will vary...
We don't throw the baby out with the bathwater, we help people learn if we have the knowledge to do so. Its why we dont jump up and down screaming heretic all that often.