God promises to stay involved through the life-long process of spiritual growth. It's in the Bible, Philippians 1:6, NKJV. "being confident of this very thing, that He who has begun a good work in you will complete it until the day of Jesus Christ"
Jesus is the source of spiritual growth. It's in the Bible, We should growing more like Jesus daily. It’s in the Bible, 2 Peter 1:5-8, NIV. “Make every effort to add to your faith goodness; and to goodness, knowledge; and to knowledge, self-control; and to self-control, perseverance; and to perseverance, godliness; and to godliness, brotherly kindness; and to brotherly kindness, love. For if you possess these qualities in increasing measure, they will keep you from being ineffective and unproductive in your knowledge of our Lord Jesus Christ.”