The Great Commission calls us to people inside the church (maybe someone needs to rededicate their lives back to God and not rely on religiosity) and to those outside of the church (reaching the unsaved). The Great Commission is for the message of Jesus to be spread across the globe. Your brothers and sisters in Christ might be scared to share the Gospel, especially if certain people with whom they might talk seem a bit intimidating. Moreover, maybe your brothers and sisters have various insecurities, but let them know you have dealt with some insecurities yourself, and remind them that God is greater than our insecurities and fears.
Also it helps to know that you don't have to know everything in order to share the Gospel with others. You just have to be a willing and available vessel to God. Don't put any extra pressure on yourself. Remember that Jesus said in Matthew 11:30, "...My yoke is easy, and My burden is light." Remember that as you share the Gospel, Jesus is with you, the Holy Spirit dwells in you, and His great power is there for you. Keep in mind that if people reject "us" while we share the Gospel, it's not really us they are rejecting, it is God Himself (Luke 10:16). So who do you know that needs to hear the Gospel? Ask God to give you the courage to tell them about this wonderful treasure you have in Christ Jesus and about how God does not want people separated from Him for eternity. It shows you care about them enough to not want to see them face hell.
I just want to encourage and inspire as many people as I can for Jesus Christ.