2 Peter 1:5
For this very reason, applying your diligence [to the divine promises, make every effort] in [exercising] your faith to, develop moral excellence, and in moral excellence, knowledge (insight, understanding)
The natural life cycle of living things is at some point it stops growing and it slowly begins to die. It is the process that God created for all living things. The exception to this process is our spiritual life, our soul. This soul never dies, it continues to grow in the knowledge of Christ for them that make every effort to exercise and develop it. The soul that ceases to grow will eventually die. “For whoever lacks these qualities of growing is blind—shortsighted [closing his spiritual eyes to the truth], having become oblivious to the fact that he was cleansed from his old sins''. Will find themselves reverting back to a life of sin. “For the wages of sin is death”. As Christian we are to continue to develop and mature in our Christian walk. Seek to live unselfishly and show brotherly love