If God, Jesus, the devil, angels, and demons were all real, we still couldn’t rely on the Christian Bible as gospal (pun intended) — it was written by humans, specifically men, who could have misunderstood or invented things. Think of it like the Snyderverse in Man of Steel: Superman is portrayed as a brooding, violent character — but that’s not his true nature. In Batman v Superman, Batman is straight-up killing people — also not his normal characterization.
So even if much of the Bible reflects real events or real beings, parts of it could still be distorted, exaggerated, or entirely made up by the people who wrote it down.
Yeah it’s hard to imagine a more petty and pathetic incel of a god than the one described in the Bible. Genocides entire populations because they don’t love him enough. Nevermind the quintillions of planets and star systems and galaxies other than the rock we live on, it’s the most recent bipedal primate on Earth that he needs affection from, on pain of eternal torment in a place he had to have created himself for that purpose. Even sent his own kid to get tacked to a board so we could be forgiven for not being deferential enough to him, even though he could have just said “meh you’re forgiven”. Or, you know, grew the fuck up and got over himself. Who was he saving us from with his infanticidal sacrifice? HIM! The daft bitch was in debt to himself and had to off his kid in a brutal and humiliating fashion to wipe the slate clean.
And on top of that, he won’t just appear and confirm his existence, which would make everyone fall in line instantly. Instead, we have to infer his existence and base our entire lives on that inference, and the only manual we have to do so was written by dick-mutilating Bronze Age numbnuts who didn’t know shit about fuck.