What is the nature of sin according to Reformed theology?

In Reformed theology, the nature of sin is seen as fundamentally rebellious—where humanity, through Adam's transgression, fell into a state of corruption. Romans 5:12 illustrates that through Adam all men inherit a sinful nature, demonstrating that all humanity is guilty and in need of redemption. This doctrine underscores the total depravity of mankind, emphasizing that apart from divine grace, there is no hope for salvation. The sin-nature, while manifesting in varying degrees, is of the same spiritual substance, emphasizing the need for every individual to look to Christ for redemption.