Some would answer that the probability is so low that it is not worth considering - without explaining why it is “so low”. The real reason - even when they are aware of the fact - is that they would lose their independence if they had to take the “possibility” of God seriously. Instead of Big Brother they would have to cope with the all-knowing Father - which is a ghastly prospect for some. You can imagine why…
We tend to judge probability by the regularity with which certain events occur, and the familiarity of the phenomena involved. Let’s take the case of the resurrection, for an example - substitute any miracle you like, but this will do for the present purpose. People coming back to life after properly dying is not an event that happens often, in our experience. If it had happened even once since it is reported to have happened in the gospels, the news media (or the gossips and chroniclers) would be all over it. Thus far, we have one, at most two, claimed historical instances of this happening.
If we enter into the realms of imaginative fiction, people coming back to life after dying is a fairly common plot point. We also know that humans have an inbuilt propensity for telling and responding to stories. Narrative is in our blood, part of our human psychological make-up. The probability of the resurrection of Jesus being a story that was made up, told and retold is far higher, considering how we tend to judge probability, than it having actually happened.
Not to say that we’re always correct in our judgements of probability, but I suspect this is where the remark comes from.
As for the judgement that many people reject the idea of a personal God from a desire for independence, this may well be the case for some people, and who knows? The fundy evangelicals might also be right that many atheists are so because they don’t want to be morally accountable to God. But there are good reasons for this. Being morally accountable to the God described in the Bible strikes a lot of people as a thoroughly
immoral choice. My suspicion is that many atheists have no problem with moral accountability - to other people, to other animals, to the environment, and to themselves - but just have no desire to invest belief in a God who, if the Bible is taken seriously, is liable to order massacres (including of children), who participates in torture of a man for the sake of a bet, who damns children for their parents’ sins, who destroyed the entire living population of the world, and who sacrificed his own son rather than forgive a debt without a payment of blood…and who, to top it all off, might not even exist.
I am inclined to think that the reason atheists are atheists isn’t because they are immoral or selfish, but because they feel no need to believe that a remarkably human-like being made the world for humans; they don’t think their lives depend upon magic in order to have value or meaning; in short, they think this life and this world are enough to be going on with. God is irrelevant.
As a possibly illuminating aside, I once heard - can’t remember where or from whom - a perfectly plausible, but probably no less miraculous, explanation of the loaves and fishes miracle variously reported in the Gospels. The traditional interpretation has it that Jesus was handed five loaves of bread and two fish and magically multiplied the quantities thereof, breaking them into pieces, then more pieces, then more pieces, until there was enough to feed 5,000 people and lots left over. The account I heard suggested that, when Jesus asked if anyone had any food, and the small boy offered him the loaves and fishes he had, and Jesus accepted them graciously and began sharing them out, this inspired the people gathered to hear him to take out their own food and share it amongst themselves; prior to this, they had been keeping their food to themselves, maybe thinking they didn’t have enough to share. When everyone who had food was minded to share it, there was plenty for everyone. Anyone who’s ever been to a pot-luck lunch knows that when everyone brings what they judge to be enough for themselves, there’s almost always more than everyone can eat. To my mind, this plausible, naturalistic explanation of the loaves and fishes miracle is far more beautiful than the magic-man interpretation, and no invocation of anything ‘supernatural’ is required - just the inspiration for generosity and cooperation.