Sin and Depravity
"Sin" is any failure to live as uprightly as Christ, who lived with perfect love for his Father and constant obedience to him. "Depravity" (literally "crookedness") is the condition of humanity which makes us necessarily wicked apart from God's saving grace in Christ. These topics are usually not discussed openly or deliberately in churches today. But they are the foundation of the gospel, because they describe what people need to be saved from.