The Gospel of Mark
And Jesus uttered a loud cry and breathed his last. And the curtain of the temple was torn in two, from top to bottom. And when the centurion, who stood facing him, saw that in this way he breathed his last, he said, “Truly this man was the Son of God!” Mark 15:37-39 (ESV)
The cross is where we truly see the Son of God, proclaimed by a centurion after Jesus had breathed his last. This is when the curtain of the temple was torn in two, symbolizing that Jesus' work was complete. The Son of God had become human to pay for the sins of the world, completing his work of reconciliation.
Mark laid out in his Gospel that it was this Jesus Christ who truly was the Son of God, not Caesar or anybody else who might try to make that claim. Mark’s very first words stated that Jesus Christ was the Son of God, and then he proceeded to fill his Gospel with all the evidence. He then ends his Gospel with the resurrection; Jesus died on the cross, but the grave did not keep him, for he had conquered death. Mark recounts how Jesus appeared to the women and his disciples, giving them the Great Commission – to proclaim the gospel to the whole creation. That same Great Commission is given to us. We, too, are called to go out into all creation, telling others that Jesus Christ is the Son of God, truly.
My guilt, O Father, Thou hast laid
On Christ, Thy Son, my Savior.
Lord Jesus, Thou my debt hast paid
And gained for me God’s favor.
O Holy Ghost, Thou Fount of grace,
The good in me to Thee I trace;
In faith do Thou preserve me.
The Lutheran Hymnal 375:5