In Luke 8:16 Jesus changes from a planting theme to the subject of light. Jesus used this theme previously in the Sermon on the Mount (Matthew 5:15). Luke shows that Jesus repeated such themes when they served his purpose in teaching his disciples. Here, Jesus tells us that light cannot be hid, and light in this context is the word of God (Luke 8:16; cf. Psalm 119:105; cf. 2Peter 1:12-21). While one might conclude that the light that cannot be hid is the believer (cf. Matthew 5:14), the context in Luke seems to indicate it is the word of God (cf. Luke 8:11). Up to this point Jesus had been speaking of the fruitfulness (or lack thereof) of the word of God in a man’s heart. I believe he continues to do so, as he changes the symbol to light.
Jesus spoke of the blessing the apostles experienced (Luke 8:10; 17) in that they were able to know and comprehend, what holy men of God in the past were unable to understand (cf. Matthew 13:16-17). Often, it was revealed to those who recorded the word of God prior to the coming of Jesus (cf. Luke 16:16) that what they were given was not for them. Rather, the word they were given from God was for people yet in the future (cf. Daniel 8:17; 10:1, 12:4-9; 1Peter 1:12). So, what was mysterious or secret to men of God in ancient times was during the time of Jesus ministry revealed to everyone in the Gospel of the Kingdom (Luke 10:23-24; cf. 1Corinthians 2:7-12; Colossians 1:25-26).
As disciples of Christ, God expects us to share the light (word of God) we’ve been given (Luke 8:16) with others. Just because God’s word was hidden in the past, doesn’t mean he intends for it to be hidden today. He has given us his Spirit, so we all might understand (John 14:26; cf. Colossians 1:9). Therefore, it would be wrong for the least of Christ’s disciples to be held in contempt by his chief disciples (Hebrews 8:10-12; cf. Luke 22:25-27; John 7:47-49).
The fruitfulness of the word God deposits in the hearts of the disciples of Jesus cannot be hid, even from those who don’ t understand the Gospel (Luke 8:10). Therefore, preaching the word of God will cause those whose hearts are hard or encumbered with many cares and worldly desires to reconsider Jesus and how he might change their lives. It is important, therefore, how we listen (Luke 8:18). The mysteries of the Kingdom will not be revealed to folks whose hearts are hard and have no value for God’s word (Luke 8:5:12). Nor can much be revealed to anyone who has no depth (Luke 8:6, 13) or to those who set their hearts on the cares and pleasures of this world (Luke 8:7, 14). Rather, the word of God is fruitful only among those disciples who have been prepared to receive it and apply it in their lives (Luke 8:8, 15).
In Luke 8:18 Jesus is speaking of retaining knowledge or possessing the secrets of the Kingdom of God (cf. Luke 8:17). Therefore, those who have such knowledge, or possess such secrets and apply them to their lives so that they bear fruit (cf. Luke 8:8, 15), will be given more. Nevertheless, those who don’t have or possess such knowledge of the Kingdom in such a way that they practice what they know and bring forth fruit to God (cf. Luke 8:8, 15), even that which he thinks he possesses, or what he has had the reputation of possessing, will be taken from him. In other words, lack of use produces forgetfulness.
When I read Luke 8:19-20, I cannot help but recall the problem John the Baptist had with hearing about Jesus’ ministry (Luke 7:18-19). A difference is placed between those whom Jesus has received into the Kingdom of God (Luke 6:13-16) and those he has not (cf. Luke 7:28; Matthew 3:13-15). Jesus’ mother and brothers and sisters desired to see him, because the authorities had claimed Jesus was beside himself and had a demon (Mark 3:20-22, 30-31). In other words, they believed what was being said about him and wished to remove him from danger. Jesus used this opportunity to show us that the word of God, if believed and practiced, brings folks into a family relationship with Jesus (Luke 8:21), and this relationship is stronger and more delightful than what one experiences with one’s physical family.
Knowing Jesus in a close relationship (Luke 8:21) is possible only when one both hears the word of God and applies it to one’s life. Thereby one brings forth fruit to God, through endurance and in the face of persecution (cf. Luke 8:13). The disciple of Jesus works patiently with God in his own life to remove what stunts his spiritual growth (Luke 8:14; cf. Philippians 2:12-13) and improves his opportunity to enjoy his walk with Christ.