Spiritual growth is the goal of Christians. It's in the Bible, II Peter 3:18, TLB. "But grow in spiritual strength and become better acquainted with our Lord and Savior Jesus Christ."
Spiritual growth results from discipline. It's in the Bible, I Corinthians 9:25, NIV. "Everyone who competes in the games goes into strict training. They do it to get a crown that will not last; but we do it to get a crown that will last forever."
God has promised continuous growth until Jesus returns. It's in the Bible, Philippians 1:6, TLB. "And I am sure that God who began the good work within you will keep right on helping you grow in His grace until His task within you is finally finished on that day when Jesus Christ returns."
Growth takes practice and is essential to the Christian life. It's in the Bible, Hebrews 5:12-14, TLB. "You have been Christians a long time now, and you ought to be teaching others, but instead you have dropped back to the place where you need someone to teach you all over again the very first principles in God's Word. You are like babies who can drink only milk, not old enough for solid food. And when a person is still living on milk it shows he isn't very far along in the Christian life, and doesn't know much about the difference between right and wrong. He is still a baby-Christian! You will never be able to eat solid spiritual food and understand the deeper things of God's Word until you become better Christians and learn right from wrong by practicing doing right."