Your note made me think of my three sons who tell me our dinner time debates at home while they were growing up were like philosophy classes. We debated everything and allowed questions about Free Will, determinism, religion, theology, politics, science you name it we debated it. And when in 2015 or so, my 3 sons took me to McDonald observatory, we spent 10 hours out and 10 hours back debating everything. My daughters-in-law all hate to hear us debate because sometimes it gets a bit raucus. They think for themselves, but they are all strong beleivers because I gave them reasons to believe, even though I don’t think they hold my flood view either. But they were taught Christianity at home. But my kids also saw my doubts, which began while they were in High School and Jr. High.
My middle son is a preacher and he told me about a month ago some statistics that say what you suggest about letting kids figure it out for themselves won’t work. while the absolute numbers from memory probably aren’t correct the order of magnitude is correct. Something like 80% of children raised in a home where the parents practice their religion and take it seriously remain Christians. A very small percentage (fixed this) remain Christian if the parents don’t practice it. The final number I am pretty sure of because it was closer to my situation. My dad and grandfather were atheists and my religious mother, a socipathic child abuser, but she did pay me to go to church rather than stay home with dad–I sold out cheaply 
. Only 1% of children who don’t go to church become Christians later in life. You are a statistical oddity. Left to our own devices few find God.
As I have said to you a lot, if you don’t like my ideas, fine, I don’t care. But telling someone to believe the bible because it is true, inspite of the historical events being untrue, does not foster a warm cuddly feeling that one is engaging in something real.
Like it or not, Christianity is a historical religion. Jesus came because Adam sinned. His resurrection is the very basis upon which our sin is taken care of. As H. G. Wells, a famous SF author since you have been fond of SF in this thread, said:
“If all the animals and man have been evolved in this ascendant manner, then there would have been no first parents, no Eden, and no Fall. And if there had been no Fall, the entire historical fabric of Christianity, the story of the first sin and the reason for an atonement, upon which current teaching bases Christian emotion and morality, collapses like a house of cards.” H. G. Wells, The Outline of History, (Garden City: Doubleday, 1961), p. 776-777
I don’t agree that evolution is incompatible with first parents, so long as we allow a bit of God’s intervention into the creation of man, but his point is well taken. If there are no first parents, no Fall then the dominoes of Christianity fall to the floor. So my views of Genesis and the flood are not for the purpose of propping up some pathetic culture, they are for maintaining the logic of Christian atonement. The YECs have a point about Jesus, supposedly the son of God, using Noah as an example. Matthew 24, 37-39 says:
“As it was in the days of Noah, so it will be at the coming of the Son of Man. 38 For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark; 39 and they knew nothing about what would happen until the flood came and took them all away. That is how it will be at the coming of the Son of Man”
If I take your position and not worry about the historicity of the flood, then I would have to ask: Did the son of God not know the flood was false? Could God not foresee what people might think about using a false statement, especially atheists? And in any event, the great Mesopotamian flood didn’t even wipe out Ur which was at the mouth of the river at that time, so how is the coming of the son of man like a bunch of people who were never wiped out when the non-flood didn’t happen? --if anything should have been wiped out in the Mesopotamian flood, it should have been the city of Ur. All of these are the atheist questions still rattling around in my mind, from my years of doubt. If we can’t answer them, how logical is our religion?