Christ answers what Islamic mercy leaves under-specified: God himself provides the sacrifice, bears the consequence of sin, unites humanity to divine life and gives sacramental means of transformation. Mercy is therefore neither arbitrary acquittal nor earned wage.
Catholic judgement begins with the shared propositions and inherited points of comparison: Muslims profess one creator, revere Abraham, pray, fast, give alms and honour Jesus and Mary in distinctive ways. These facts deserve exact description and do not erase decisive contradictions.
The Qurʾānic account of Jesus denies or obscures truths already publicly attested in earlier apostolic sources: divine sonship, crucifixion, redemptive death and resurrection. A later text cannot overturn earlier evidence merely by claiming correction; it must supply historical grounds.
The Trinity is one divine essence in three distinct persons, not a triad of gods and not a biological generation. Polemics that answer a tritheistic or corporeal doctrine do not yet answer Nicene Christianity.
The judgement of Islam concerns doctrines, laws and historical claims; it does not license hatred or injustice toward Muslim persons. No outward force can produce the supernatural act of faith. Yet error possesses no moral right as error, and civil toleration of false worship, when grave reasons of the common good require it, is a prudential permission rather than recognition of equal religious rights. The Church must therefore proclaim Jesus Christ openly and refute doctrines that deny His divinity, Cross, Resurrection and Church.
The appropriate response to grace, salvation and christ is neither contempt nor vague admiration. It is accurate quotation, patient distinction, positive proof of the Catholic position and an invitation to the fullness of truth and sacramental life in Christ.