Just like ancient people didn't know what a nuclear bomb was, they naturally wouldn't ask those who truly knew of its existence what a nuclear bomb is.
Evil Spirits wanted to summon their origin, the Great Evil God, because the Rebellion God, as referred to by them, appeared first and unsettled them, leading to a search for new cooperation; meanwhile, the information they revealed pertained to the Gate of Hell. If the Great Evil God was to revive in Hell, without tearing open a sufficiently large rift, the Great Evil God certainly couldn't cross over.
Therefore, the origin fragment of the Great Evil God must first be transferred to the Mortal Realm.
This is the uniliteral claim of the Evil Spirits, and Bazel isn't from some ignorant small mountain village. The Evil Spirits seemed very convincing, but what about in reality? It would be prudent to just listen to their claims and not take them too seriously—believing them outright would be foolish.