What is the response to the Christian assertion that the sacrificed son was Isaac, not Ishmael, and that this is mentioned in the Gospel?

There are two ways to respond to the Christians' claim that Isaac (peace be upon him) was the sacrificed son:

The first way: The Christian scriptures (the Gospels) lack the conditions for acceptance and credibility. They are inconsistent in identifying their authors, narrators, dates of writing, and the extent of the changes that have occurred to them.

The second way: The narratives within the Gospels themselves are inconsistent and contradictory regarding the sacrificed son. While they mention his name as "Isaac," they describe him as the only son and the firstborn, a description that applies to Ishmael before Isaac's birth. Furthermore, Allah the Almighty gave Abraham the good news of Isaac, and then Jacob after him. How could He command him to slaughter him while he was young, knowing that he would live and have offspring? This is confirmed by the Holy Quran in Surahs As-Saffat and Hud, where it clarifies that the good news of Isaac came after the story of the sacrificed son (Ishmael), and that he would have progeny (Jacob), which refutes the idea that he was the one to be sacrificed.