A.T. Robertson 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)

If thou art the Son of God (ε υιος ε του θεου). More exactly, "If thou art a son of God," the very language of the devil to Jesus (Matthew 4:3) in the early temptations, now hurled at Jesus under the devil's prompting as he hung upon the Cross. There is allusion, of course, to the claim of Jesus under oath before the Sanhedrin "the Son of God" (ο υιος του θεου) and a repetition of the misrepresentation of his words about the temple of his body. It is a pitiful picture of human depravity and failure in the presence of Christ dying for sinners.