The Superhero Database Classification number, or SHDB Class, is a number that represents the overall 'power' of a character. All traits of a character are used for calculating the Classification.
What it DOESN'T mean
This doesn't mean that a higher class would always beat a lower class character. But the bigger the difference in Class is, the more obvious it is who'll win in a fight.
How is this calculated
( INT^1.3 + (STR*0.5 )^2 + (SPE*0.5)^2 + DUR^1.6 + (POW + (SPS*SPL))^2 + COM^1.8 ) ^ TIER
Super Power Score and Level
Every Super Power has a score (SPS) that is used to calculate the Class. Each Super Power also has 3 levels (SPL). The level is set when connecting that Super Power to a character. The level determines the final score, of the Super Power, being used in the calculation.
Dude, don't ever think that "omnipotent" character can't be defeated, this is just a fiction.
Cosmology also plays an important role and Eru is not God like in the real world.
Eru is only a fictional character and has limitations, he clearly does not have the power and feats that put him at Marvel's cosmic level.
by the way you do your cross-verse scaling bias well, viewing one type of comic fiction (eg. Superhero stories) as inherently more powerful than another type of Fantasy novel such as Lord of the Rings by J.R.R. Tolkien. as in fact, comparisons between completely separate fictional settings run by different authors break down because there is no evidence that the authors planned directly corresponding power scaling between their separate fictional universes.