How do we know that mortification of sin is necessary?

Mortification of sin refers to the believer's responsibility to actively put to death sinful habits and desires. The New Testament underscores this necessity, particularly in Romans 8:13, where it states that through the Spirit, believers must put to death the deeds of the body. This concept is vital as it reminds us that the power of divine grace is at work in us, and neglecting this practice can lead to a softening of our resolve against sin. Recognizing the need for mortification ultimately leads to spiritual growth and an increase in holiness.