Why is it important not to mix law and grace?

In Mark 2:21-22, Jesus uses parables to illustrate that attempting to combine new teachings (grace through Him) with old ways (the law) leads to greater destruction. The Pharisees embodied this error by trying to earn righteousness through their excessive rituals and legalism, which only revealed their spiritual deadness. Paul reaffirms this in Galatians 5:4, stating that those who seek justification through the law have fallen from grace. Understanding salvation as a pure work of grace prevents us from relying on our efforts and keeps our focus on Christ, the only source of true righteousness.