After billions of years of observing his creations, God had become somewhat cynical. He considered human nature to be toxic and was willing to let Amara destroy everything seemingly out of spite against humans , for fighting wars in his name and then begging him to fix everything, and generally not taking responsibility for their failures. He also considers his creations to be experiments and also revealed that he abandoned the angels and humanity because they'd disappointed him.  He later admits to Dean that it's more than disappointment: while he'd once taken an active role in his creations' lives, he realized that he was hindering them more than anything and he needed to let them find their own way like a parent with their child. Despite everything that's happened since he did so, God believes he made the right decision. 
Eep. What’s interesting about this, though, is how it’s a pretty clear reflection of how Light is received and framed by his story and the audience. For all his villainy, Light is the viewpoint character in all iterations of Death Note , and the framing is such that even if his methods are abhorred, the audience is encouraged to empathize with him. There’s something relatable about his drive to take matters into his own hands, something that taps into our worst impulses toward vengeance and self-righteousness. That’s what’s scary about the Death Note. If we all stopped to think about it, we’d probably have names we’d want to write down.
The deepness of the Mark's colour is connected to Voldemort's physical health. When Voldemort suffered his first defeat, the Marks on the Death Eaters faded, but as he began regaining his strength, the faded marks became clearer, and burnt slightly, a sign of Voldemort's return to his Death Eaters; the burn may be sudden and stings rather sharply, as Snape suddenly gripped where his mark during the night Harry Potter was solving the Golden egg riddle.  Death Eaters could also use it to signal Voldemort by pressing on their Dark Marks. Bearing this mark also allows the Death Eaters to bypass a cursed barrier that is also invented by Voldemort.  During the height of the Second Wizarding War , they were under orders to only signal Voldemort if they had successfully captured Harry Potter , or face severe penalties. After Voldemort was defeated for the final time, the dark marks faded to a scar, similar to Harry's lightning-bolt scar. They would no longer burn, but would remain nevertheless. There is no possible way of getting rid of the Dark Mark.