A Wolf's Howl, A Fairy's Wing - Chapter 591 - Undo it...

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

- Description from Novelupdates

After a god screws up and accidentally takes high schooler Shou’s life, he offers him reincarnation with a gift to make up for it. Shou asks to retain all his old memories for the new life. Shou is reborn as Will, a noble’s son in a world where magic use is common and involves knowledge of kanji characters. With all his memories, he’s a brilliant toddler, and when he experiments with magic, he finds that he has an amazing talent for it! What’s more, though he was smart but unloved in his old life, in his new life he has a mother and a father who both love him deeply. His future as Will is looking very bright and cool!

In a prehistoric age when all things in the world had no names,God descended.God created life, reason, light...He separated the darkness, and brought life from the underwater cradle to land.He bestowed language upon the ape-men, freeing them from the realm of beasts.He chose the first prophet of the world, who led the entire civilization's history, the descendants of the prophet later established a great nation.......In the golden age that followed, people left God and dispersed across the world.Many things were forgotten, leaving history to be buried by time.Yet life is a return.People will eventually remember,In this story, God first loved the world.