How do we respond to someone who claims that asserting the eternality of the nawʿ (species/kind)—meaning its perpetual existence, without beginning or end, even while its individual members are created (originate in time)—is a blatant deviation from creed, and that it is a sophistry and a deception?

The verses mentioned in the question are from Ibn al-Qayyim's Nuniyyah, and the title "Ibn Zafil" is not known for him; rather, some opponents slandered him with it. This issue is precise and should not preoccupy common Muslims, as it is not among the fundamentals of religion. Sheikh al-Islam Ibn Taymiyyah discussed it to demonstrate the invalidity of the philosophers' doctrine and the weakness of the mutakallimin's (speculative theologians') arguments regarding the existence of the Creator and the temporality of the world. The doctrine of the Ahl al-Sunnah wal-Jama'ah is the permissibility of events without a beginning, and this does not mean agreement with the philosophers who assert the world's eternity, for Ibn Taymiyyah established that everything other than Allah is temporal and created.

The summary of what a Muslim must know concerning this matter: 1. Allah Almighty is the First, before whom there was nothing. 2. Allah Almighty is eternally and everlastingly characterized by attributes of perfection, including His being a Creator of whatever He wills, and He was never inactive concerning action. 3. Everything other than Allah Almighty is created by Him and came into being after not having existed.

It is advised not to frequent forums that do not revere the methodology of the Salaf, as error in matters of creed is dangerous.