Discipleship is cultivating in yourself, and reproducing in others, measurable spiritual progress through the vehicle of Christian friendship. -Kurt Gebhards
Matthew 19"Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit, teaching them to observe all that I commanded you; and lo, I am with you always, even to the end of the age."
Spiritual progress is detailed in 2 Peter 1:3-8, "seeing that His divine power has granted to us everything pertaining to life and godliness, through the true knowledge of Him who called us by His own glory and excellence. For by these He has granted to us His precious and magnificent promises, so that by them you may become partakers of the divine nature, having escaped the corruption that is in the world by lust. Now for this very reason also, applying all diligence, in your faith supply moral excellence, and in your moral excellence, knowledge, and in your knowledge, self-control, and in your self-control, perseverance, and in your perseverance, godliness,and in your godliness, brotherly kindness, and in your brotherly kindness, love. For if these qualities are yours and are increasing, they render you neither useless nor unfruitful in the true knowledge of our Lord Jesus Christ. "
So, spiritual growth includes:
(1) increasing in your knowledge and understanding of God's Word,
(2) decreasing in your frequency and severity of sin,
(3) increasing in your practice of Christ-like qualities
(4) increasing in your faith and trust in God.
Perhaps the best summary of spiritual growth is becoming more like Jesus Christ. In 1 Corinthians 11:1, Paul says, "Follow my example, as I follow the example of Christ." Jesus Christ is the ultimate example of what it truly means to be spiritual.
Spiritual growth is a life-long process of manifesting the acts of the flesh (Galatians 5:19-21) less and less and producing the fruit of the Spirit (Galatians 5:22-23) more and more. God is the one who causes all growth, so we should ask him to cause us to grow as we are obedient to His Word. What does spiritual growth look like? Galatians 5:22-23 has the answer, "But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness, gentleness and self-control. Against such things there is no law." If you are becoming more loving, more joyful, more kind, more self-controlled, etc., then you can rest assured that spiritual growth is genuinely occurring in your life.
God works in different people in different ways. Some people grow rapidly, while others grow slowly, but steadily. Our focus should not be on comparing ourselves with others, but on comparing ourselves with God's Word. The Scriptures are the mirror to show us what we are like spiritually and to shine light on the areas that need to experience and learn spiritual growth. James 1:23-25 declares, "Anyone who listens to the word but does not do what it says is like a man who looks at his face in a mirror and, after looking at himself, goes away and immediately forgets what he looks like. But the man who looks intently into the perfect law that gives freedom, and continues to do this, not forgetting what he has heard, but doing it - he will be blessed in what he does." –Some of this taken from allaboutgod.com