How does Christ teach us about sin in the Sermon on the Mount?

Christ's teachings in the Sermon on the Mount clarify that sin goes beyond external actions to the internal state of the heart. For example, he explains that anger towards a brother is equated with murder in the heart (Matthew 5:21-22), and lustful thoughts constitute adultery (Matthew 5:27-28). These teachings emphasize that our natural sinful condition—conceived in Adam—leads us to be guilty before God not just for our actions but for our very thoughts and intentions. Thus, the law reveals our total depravity and inability to achieve righteousness on our own. This is a crucial lesson for believers as it drives us to rely entirely on Christ for salvation and transformation, highlighting the need for divine grace, which alone can change the heart and enable genuine obedience.