Christ says we are to "let" our lights shine. In other words, when you get right with God and are filled with the Holy Spirit, He will simply shine through you. God is the light that shines within and through His church as the light of the world. The same word the Bible uses for light in Matthew 5 to describe Christ’s Church also describes Christ Himself in John 8:12.
There are many today who suggest that the church would be better off if we watered down the message of the Gospel for the sake of our witness.
These people say things like, "You're too hard on people. Don't be so dogmatic regarding Christ's teaching. You're going to run people off."