How do we know what Jesus accomplished by His death?

Jesus accomplished several key things through His death: He was made sin, He was cursed under God's law, and He fulfilled that law perfectly on behalf of His people. 2 Corinthians 5:21 states that God made Jesus to be sin for us, ensuring that His righteousness is now credited to believers. Jesus' substitutionary death is a fulfillment of God's justice, showing that through one man's obedience, many are made righteous (Romans 5:19). His work achieved the eternal redemption for those God gave Him to save, thereby glorifying God through every aspect of His earthly ministry.