Charles Ellicott Commentary Matthew 27:40

"and saying, Thou that destroyest the temple, and buildest it in three days, save thyself: if thou art the Son of God, come down from the cross." — Matthew 27:40 (ASV)

You who destroy the temple — Our Lord had not been formally condemned on this charge, as the evidence was insufficient. However, it had clearly impressed itself on the minds of the people and was probably what most influenced them to demand His death. The other words, If thou be the Son of God, referred to the actual condemnation on the grounds of blasphemy (Matthew 26:64–65).

We may reverently consider that the form of this taunt recalled the temptation in the wilderness. Then, as now, the words If thou be the Son of God were a challenge from the Power of Evil. Now, as then, they were met by the strength of Faith. To accept the challenge would have been to show that He did not trust the Father, just as it would have been a lack of faith—not faith itself—to have thrown Himself from the pinnacle of the temple, and therefore to disown His Sonship in the very act of claiming it.