Matthew 27:45 We do not know how the darkness occurred, but it is clear that God caused it. Nature testified to the gravity of Jesus' death, while Jesus' friends and enemies alike fell silent in the encircling gloom. The darkness on that Friday afternoon was both physical and spiritual.
Matthew 27:46 Jesus was not questioning God; He was quoting the first line of Psalm 22 - a deep expression of the anguish He felt when He took on the sins of the world, which caused Him to be separated from His Father. This was what Jesus dreaded as He prayed to God in the garden to take the cup from Him. The physical agony was horrible, but even worse was the period of spiritual separation from God. Jesus suffered this double death so that we would never have to experience eternal separation from God.
Matthew 27:47 The bystanders misinterpreted Jesus' words and thought He was calling for Elijah. Because Elijah ascended into heaven without dying (2 Kings 2:11), they thought he would return again to rescue them from great trouble (Malachi 4:5). At the annual Passover feast, each family set an extra place for Elijah in expectation of his return.
Matthew 27:51 The temple had three main parts - the courts, the Holy Place (where only the priests could enter), and the Most Holy Place (where only the high priest could enter, and only once a year, to atone for the sins of the nation (Leviticus 16:1-35). The veil (curtain) separating the Holy Place from the Most Holy Place was torn in two at Christ's death, symbolizing that the barrier between God and humanity was removed. Now all people are free to approach God because of Christ's sacrifice for our sins.