What can we learn about sin and the cross? 

Rob Ventura explains in this video that Christ laid His life down for His place. He was punished in our place and made full atonement for our sins.  

He cried out saying, “It is finished.” There was nothing left for Him to do. The sin of His people was atoned for on the cross on the day that He died in our place. He made satisfaction to God for the sins of the people for all time. 

Romans 3:23-25 (NKJV) - "[F]or all have sinned and fall short of the glory of God, being justified freely by His grace through the redemption that is in Christ Jesus, whom God set forth as a propitiation by His blood, through faith, to demonstrate His righteousness, because in His forbearance God had passed over the sins that were previously committed."

Jesus died for his people. He made a 100% satisfaction to God Almighty for the sins that we committed on the cross. Jesus laid his life down for us. He willingly took the sins of his people in his own holy body and up to the tree and he was punished in our place and he made a full atonement shedding his blood canceling out all of our guilt to the end that when Jesus was on the cross He didn't cry out saying to be continued. He cried out saying it is finished.

It is all finished. It was atoned for on Calvary on the day He died in our place and the atonement and the effects will continue on for all eternity. He made a once for all satisfaction to God Almighty for all the sins of His people.