Over and over in the New Testament, we are told to serve others, to let our light shine.  But the reason isn't simply so that we can help other people, which is, of course a blessed thing in itself.  We have been ordained to bring others to faith, to guide other people into the Kingdom of God. When we are told by Jesus: In the same way, let your light shine before others, so that they may see your good works and give glory to your Father in heave, we are being instructed to motivate others to give glory to God.