@Azsy
Nie Li? Piss weak? Oh man are you ever stupid.
Demon Lord is just currently stronger than him... and everyone. In the entire world. Everyone is weaker than the #1, that's how that shit works. He's technically TOO strong for the world they live in, he's a half-step Heavenly Fate, which he already said so that's not a spoiler.
A Legend Rank or Spiritual God is basically nothing before him. Like killing chickens. He's not joking when he says he can easily kill them all and wipe Glory City off the map by himself (a city that regularly survives waves and waves of powerful demon beasts numbering in the millions or billions - this guy can destroy it with one of his four hands). ONLY Nie Li is any kind of threat to him, but they're surrounded by Nie Li's friends and loved ones, so they're being held hostage so Nie Li doesn't go all-in after the Demon Lord.