Is it true that speaking about God without knowledge is unforgivable on the Day of Resurrection, because some say it is a greater sin than Shirk (polytheism), and if it is forgivable, then how can the statement that it is a greater sin than Shirk and the interpretation of the Noble Verse be reconciled?

Ibn al-Qayyim mentioned that the genus of speaking about Allah without knowledge is more severe than the genus of shirk (polytheism); it is the root of shirk and disbelief, and upon it are founded innovations and misguidance. The distinction between individuals and genera is important, for not every individual instance of speaking about Allah without knowledge is more severe than every individual instance of shirk. Some instances of speaking about Allah without knowledge do not reach the level of shirk, while others fall within shirk and even exceed it, such as attributing vices to Allah or associating others with Him. This latter type may be greater than the genus of shirk and necessitates the withholding of forgiveness.