Several months ago?
If John's memory served him right, wasn't that precisely when he had emerged from the Godslayer Temple?
That is to say, his act of slaying Devil Azazel triggered Azazel's Soul Seed in the Abyss to begin its automatic revival...
Suddenly, as if piecing together a puzzle, John asked with an air of utmost gravity, "So, you're saying that once Azazel's Soul Seed in the Abyss accumulates enough dark energy, it will revive?"
Mammon nodded emphatically, a mocking smile gracing his face.
"Exactly. Those sanctimonious deities have bungled their own plans by erasing Azazel. I don't know what they were thinking. They should know that Devils never truly die, yet they went ahead and committed this senseless act."
"This instead allows His Majesty Azazel to break free from the shackles of his sealing, to return to the embrace of darkness once more," Mammon continued.