The Heidelberg Catechism: Lord's Day 4
9. Question: Is God, then, not unjust by requiring in His law what man cannot do?
Answer: No, for God so created man that he was able to do it. But man, at the instigation of the devil, in deliberate disobedience robbed himself and all his descendants of these gifts.
 Gen. 1:31.  Gen. 3:13; John 8:44; I Tim. 2:13, 14.  Gen. 3:6.  Rom. 5:12, 18, 19.
10. Question: Will God allow such disobedience and apostasy to go unpunished?
Answer: Certainly not. He is terribly displeased with our original sin as well as our actual sins. Therefore He will punish them by a just judgment both now and eternally, as He has declared: Cursed be every one who does not abide by all things written in the book of the law, and do them (Galatians 3:10).
 Ex. 34:7; Ps. 5:4-6; 7:10; Nah. 1:2; Rom. 1:18; 5:12; Eph. 5:6; Heb. 9:27.  Deut. 27:26.
11. Question: But is God not also merciful?
Answer: God is indeed merciful, but He is also just. His justice requires that sin committed against the most high majesty of God also be punished with the most severe, that is, with everlasting, punishment of body and soul.
 Ex. 20:6; 34:6, 7; Ps. 103:8, 9.  Ex. 20:5; 34:7; Deut. 7:9-11; Ps. 5:4-6; Heb. 10:30, 31.  Matt. 25:45,46.
Be on your guard; stand firm in the faith; be courageous; be strong. Do everything in love.