Perhaps the reason why some never share good news is because they have never received it or experienced it. For the follower of Jesus there is a never ending supply of Good News that was never meant to be kept.

"And Jesus came and spoke to them, saying, 'All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you; and lo, I am with you always, even to the end of the age.'” – Matthew 28:18–20