Matthew 27:40 - Ellicott's Commentary On The Whole Bible

Thou that destroyest the temple. — Our Lord had not been formally condemned on this charge, the evidence being insufficient, but it had clearly impressed itself on the minds of the people, and was probably that which most worked upon them to demand His death. The other words, “If thou be the Son of God,” referred to the actual condemnation on the ground of blasphemy (Matthew 26:64-65). We may reverently think of the form of the taunt as having recalled that of the Temptation in the Wilderness. Then, as now, the words “If thou be the Son of God” were as 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 not faith, but want of faith, to have cast Himself from the pinnacle of the Temple, and therefore to disown His Sonship in the very act of claiming it.