What is the interpretation of the noble verse, "Indeed, it was a great sacrifice," which a Christian cited to argue for the prophets' deliverance from calamities, in the context of a discussion about the crucifixion of Christ?

The Christians have no evidence for their falsehood. The aforementioned sentence is not from the Book of Allah the Almighty. Rather, what is found in it is His saying: ﴿And We ransomed him with a great sacrifice﴾, and that is in the context of the story of the ransom of Allah's Prophet Ishmael. Christ Jesus son of Mary was not killed nor crucified, but rather Allah raised him to Himself. Indeed, the one who was killed was his look-alike. Allah the Almighty said: ﴿And for their disbelief and their saying against Mary a great slander, And their saying, "Indeed, we have killed the Messiah, Jesus, son of Mary, the Messenger of Allah." And they did not kill him, nor did they crucify him; but [rather] it was made to appear to them [as such]. And indeed, those who differ over it are in doubt about it. They have no knowledge of it except the following of assumption. And they did not kill him for certain. Rather, Allah raised him to Himself. And ever is Allah Exalted in Might and Wise.﴾ One who undertakes to invite Christians to Islam must be qualified for that.