Heidelberg Q. 3. From where do you know your sins and misery?
A. From the law of God.

Heidelberg Q. 4. What does God's law require of us?
A. Christ teaches us this in a summary in Matthew 22: You shall love the LORD your God with all your heart, and with all your soul, and with all your mind. This is the great and first commandment. And a second is like it, You shall love your neighbor as yourself. On these two commandments depend all the law and the prophets.

Heidelberg Q. 5. Can you keep all this perfectly?
A. No, I am inclined by nature to hate God and my neighbor.