The Mujasima believe that Allah ﷻ is attributed with “emergent”, yet “uncreated” qualities. That is to say: He lacked a quality that He then brings into existence for Himself, and yet this emergent quality is uncreated. This is perhaps the most ridiculous of all their beliefs, and that is for many reasons. We list three below.
First to believe that Allah ﷻ brought something into existence, is to believe that He created it. After all, this is what “create” means. So claiming “Allah brought His qualities into existence, and those qualities are uncreated”, is the equivalent of saying “Allah created His qualities, and those qualities are uncreated”. This is of course, a blatant contradiction.
Second Allah ﷻ is changeless. This is because beings with a potential to change are necessarily emergent, whereas Allah is without beginning. And to claim that He is attributed with emergent qualities, is to claim that He changed. Thus, to claim that He is attributed with emergent qualities, is to claim that the changeless being changed. This is once again, contradictory.
Third is the argument Imam Fakhr Al-Deen Al-Razi presents in his Al-Masa’il Al-Khamsoon:
|We ask [the Mujasim]: this attribute that emerged within the being of Allah, is it an attribute of perfection or not?
If the Mujasim responds with the affirmative, then we tell him: before this attribute emerged into existence, Allah’s being was lacking this perfection. And such a thing is impossible [since a perfect being cannot lack perfection].
And if the Mujasim responds with the negative, then we tell him: in this case, it would be impossible for this quality to emerge within the being of Allah. That is because the qualities of Allah are all perfect, and this is by the consensus of all thinkers.
With the above, it becomes clear that it is impossible for qualities to emerge within the being of Allah.
 If a quality were emergent, then this would mean that Allah ﷻ transitioned from a state of lacking this quality, to a state of being attributed with said quality. This is a change.
 Whatever has the potential to change is inseparable from accidents. And that which is inseparable from accidents is emergent. Therefore, whatever has the potential to change is emergent. And since Allah is not emergent, then He is necessarily immutable. More on this here.