Question 16 – Why must He be a true and righteous man?

Answer – He must be a true man because the justice of God requires that the same human nature which has sinned should pay for sin.1 He must be a righteous man because one who himself is a sinner cannot pay for others.2

1 Rom: 5:12, 15; I Cor. 15:21; Heb. 2:14-16. 2 Heb. 7:26, 27; I Pet. 3:18.

Question 17 – Why must He at the same time be true God?

Answer – He must be true God so that by the power of His divine nature1] He might bear in His human nature the burden of God's wrath,2 and might obtain for us and restore to us righteousness and life.3

1 Is. 9:5. 2 Deut. 4:24; Nah. 1:6; Ps. 130:3. 3 Is. 53:5, 11; John 3:16; II Cor. 5:21.

Question 18 – But who is that Mediator who at the same time is true God and a true and righteous man?

Answer – Our Lord Jesus Christ,1 whom God made our wisdom, our righteousness and sanctification and redemption (I Corinthians 1:30).

1 Matt. 1:21-23; Luke 2:11; I Tim. 2:5; 3:16.

Question 19 – From where do you know this?

Answer – From the holy gospel, which God Himself first revealed in Paradise.1 Later, He had it proclaimed by the patriarchs2 and prophets,3 and foreshadowed by the sacrifices and other ceremonies of the law.4 Finally, He had it fulfilled through His only Son.5

1 Gen. 3:15. 2 Gen. 12:3; 22:18; 49:10. 3 Is. 53; Jer. 23:5, 6; Mic. 7:18-20; Acts 10:43; Heb. 1:1. 4 Lev. 1:7; John 5:46; Heb. 10:1-10. 5 Rom. 10:4; Gal. 4:4, 5; Col. 2:17.