What does it mean that God's attributes are not active, and does this negate them from having any actual attribute such as mercy for God's sight, or power for God's will? And must a person affirm that God alone has mercy for everything, and that the attributes have no mercy for anything?

Supplicating to attributes [of Allah] is polytheism (shirk) and is impermissible. Its meaning is that supplicating to an attribute and calling upon it implies its detachment and separation from the One described, as if it were something other than Him. Thus, whoever supplicates to an attribute independently is like one who supplicates to other than Allah. Sheikh al-Islam Ibn Taymiyyah said: "As for supplicating to His attributes and words, it is disbelief (kufr) by the consensus of Muslims." Ibn Uthaymeen clarified that the reason this supplication is polytheism is the notion that the attribute is separate from Allah and independent of Him. As for what is mentioned in the hadiths regarding seeking refuge in Allah's attributes, its reality is that it is seeking refuge in Allah, interceding with Him through these attributes.