The Heidelberg Catechism: Lord's Day 5
12. Question: Since, according to God's righteous judgment we deserve temporal and eternal punishment, how can we escape this punishment and be again received into favor?
Answer: God demands that His justice be satisfied. Therefore full payment must be made either by ourselves or by another.
 Ex. 20:5; 23:7; Rom. 2:1-11.  Is. 53:11; Rom. 8:3, 4.
13. Question: Can we ourselves make this payment?
Answer: Certainly not. On the contrary, we daily increase our debt.
 Ps. 130:3; Matt. 6:12; Rom. 2:4, 5.
14. Question: Can any mere creature pay for us?
Answer: No. In the first place, God will not punish another creature for the sin which man has committed. Furthermore, no mere creature can sustain the burden of God's eternal wrath against sin and deliver others from it.
 Ezek. 18:4, 20; Heb. 2:14-18.  Ps. 130:3; Nah. 1:6.
15. Question: What kind of mediator and deliverer must we seek?
Answer: 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.
 I Cor. 15:21; Heb. 2:17.  Is. 53:9; II Cor. 5:21; Heb. 7:26.  Is. 7:14; 9:6; Jer. 23:6; John 1:1; Rom. 8:3, 4.
Be on your guard; stand firm in the faith; be courageous; be strong. Do everything in love.