1 John 2:5

But whoever habitually keeps His word and obeys His precepts (and treasures His message in its entirety), in him the Love of God has truly been perfected (it is completed and has reached maturity). By this we know (for certain) we are in Him:

We will develop our spiritual strength if we treasure His word and keep it close to our hearts. Just as a child wishes to grow to physical maturity, we are to mature and grow as Christians in our faith. Our lives, whether we succeed or fail, depend on it. We are the representatives of heaven on earth, and our lives are to reflect Jesus.