Take the concept found in
Isaiah 5:4, about
“What more could have been done to My vineyard,” (NKJV) and look at that in light of the Cross, where God offered Himself as a sacrifice for our sins, paying with His flesh for our violation of His law. What more could have been done for us than what He did there? How does dwelling on the Cross give us assurance of salvation and motivate us to repent and change our ways?