Heidelberg Q. 15. What kind of mediator and deliverer must we seek?
A. One who is a true and righteous man, and yet more powerful than all creatures; that is, one who is at the same time true God.

Heidelberg Q. 16. Why must He be a true and righteous man?
A. He must be a true man because the justice of God requires that the same human nature which has sinned should pay for sin. He must be a righteous man because one who himself is a sinner cannot pay for others.

Heidelberg Q. 17. Why must He at the same time be true God?
A. 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.