“In the same way, let your light shine before others, that they may see your good deeds and glorify your Father in heaven.”
Why does Jesus tell His disciples to “let your light shine?” Most good deed doers that I know are more than happy to display their good deeds. And when people see these “good deeds” the response is more often jealousy, contempt or praise for the good deed doer, rather than glorifying God.
“Light” speaks of knowledge or revelation. To “let your light shine” is to illuminate God's glory. When people look at your good deeds, what truth is revealed? Do they learn that you are a good guy? Do they see that you are a show-off? Or do they gain insight into the glory of your Father in Heaven?