Why must He at the same time be true God?

He must be true God so that by the power of His divine nature He might bear in His human nature the burden of God’s wrath, and might obtain for us and restore to us righteousness and life.

Proofs

• He must be true God so that by the power of His divine nature (Isaiah 9:5)
• He might bear in His human nature the burden of God’s wrath, (Deuteronomy 4:24; Nahum 1:6; Psalm 130:3)
• and might obtain for us and restore to us righteousness and life. (Isaiah 53:5; Isaiah 53:11; John 3:16; 2 Corinthians 5:21)