Attributes such as wrath and joy are regarded as acts of the Most High Lord. In reality, these are attributes of the acts of the Lord of Worship.
عن هشام بن الحکم فی حدیث الزندیق الذی سأل أبا عبد الله ع فکان من سؤاله أن قال له فله رضا و سخط فقال أبو عبد الله ع نعم و لکن لیس ذلک على ما یوجد من المخلوقین و ذلک أن الرضا حال تدخل علیه فتنقله «5» من حال إلى حال لأن المخلوق أجوف معتمل «6» مرکب للأشیاء فیه مدخل و خالقنا لا مدخل للأشیاء فیه لأنه واحد واحدی الذات واحدی المعنى فرضاه ثوابه و سخطه عقابه من غیر شیء یتداخله فیهیجه و ینقله من حال إلى حال لأن ذلک من صفه المخلوقین العاجزین المحتاجین.
الکافی (ط - الإسلامیه)، ج1، ص: 110
Hisham ibn al-Hakam relates that among the questions posed by the heretic to Imam al-Sadiq (AS) was this: “Does God experience pleasure and anger?” The Imam replied, “Yes, but not in the way these states are found in created beings. Pleasure is a state that comes upon a person and shifts him from one condition to another. A created being is hollow, formed and composite; things can enter into him. But nothing can enter our Creator, for He is One—one in essence, one in meaning. His pleasure is His reward, and His anger is His punishment, without anything entering into Him, stirring Him or changing Him from one state to another. Such changes are attributes of created beings, who are frail and dependent.”
Al-Kāfī (Islamic edition), vol. 1, p. 110
Regarding divine mercy, it should be noted that the special mercy of God, the Most Merciful of the merciful, extends only to the faithful, while the unbelievers are deprived of it.
الأحزاب : 43 هو الذی یصلی علیکم و ملائکته لیخرجکم من الظلمات إلى النور و کان بالمؤمنین رحیما
He is the One who sends blessings upon you, as do His angels, to bring you out of darkness into light. And He is ever Merciful to the believers.
It should also not be forgotten that “Allah,” while being “the Most Merciful of the merciful,” is also “the Sternest in punishment.” That is, God’s mercy is manifested toward the faithful through His reward for them, while His wrath is manifested toward the unbelievers through His punishment; both are acts of the Real.