The response to him is as follows:
As for His acts and rulings being grounded in wisdom, Ahl al-Sunnah have two well-known positions on this matter, and disagreement exists within each of the four schools. In discussions of fiqh and other subjects, however, the predominant position among them is to affirm such grounding. Regarding the fundamentals of religion, some explicitly affirm it, while others reject it. The majority of Ahl al-Sunnah affirm wisdom and wise purpose in His acts and rulings.
As for the term “purpose,” the Mu'tazila explicitly use it, and they are among those who affirm the leadership of Abū Bakr, Umar, and Uthmān [may Allah be pleased with them] (1).
Among jurists and others, however, this term suggests a kind of deficiency—either injustice or need. When many people say, “So-and-so has a purpose in this,” or, “He did this for a purpose of his own,” they mean that he acted out of whim and a reprehensible desire. Allah is exalted above that. Ahl al-Sunnah therefore use such terms as wisdom, mercy, and will, as well as other expressions found in the revealed texts.
[A group of the Mu'tazila who affirm divine decree also use the term “purpose.” They say that He acts for a purpose, as is likewise found in the words of a group affiliated with the Sunnah] (2).
As for his statement:
“He commits injustice and acts in vain” (3),
no one among the Muslims says that Allah does anything that constitutes injustice (4) on His part, or any act of futility on His part. Exalted is Allah above that.