What does the Bible say about the flesh and sin?

In 1 Samuel 15, the Amalekites are used as a symbol of the flesh, illustrating the need to utterly destroy any aspect of our old nature that seeks to take credit for salvation. The flesh, or the old man, is characterized by sin and rebellion against God. Paul describes this struggle in Romans 7, acknowledging that within him dwells no good thing. To be reconciled to God, perfection is required, which can only be achieved through Christ, who puts away sin and offers salvation to those who trust in Him. The call to crucify the flesh is a command rooted in the necessity for believers to recognize their utter dependency on Christ for salvation.