Growing spiritually is about your relationship with Christ. Don't be satisfied to remain where you are spiritually without growing. But grow in the grace and knowledge of our Lord and Savior Jesus Christ (2 Peter 3:18). That statement summarizes your spiritual growth.
Growing spiritually involves grace and knowledge. The knowledge comes from your Bible. A proper diet is necessary to maintain good health. Likewise, feeding upon God's word in the Bible is necessary for your spiritual growth in Christ. Knowledge must also include grace, which is the unmerited favor of God.
Knowledge of God's word brings faith. So then faith comes by hearing, and hearing by the word of God (Romans 10:17). You believe what you know is true. Increased knowledge of Christ should lead to increased faith and assurance in Christ. That is the foundation for growing spiritually.
Growing spiritually is in the grace of Christ. Learn to trust more and more in the grace of God in Christ. God allows us to be in situations beyond our ability, that we may not trust in ourselves but in Christ. Our impossibilities are always His possibilities. With Him all things are possible. Jesus said, For without me you can do nothing (John 15:5). That lesson leads us to spiritual growth in Christ, as we depend upon Him in all of life's situations.
