Well known atheist Penn of Penn & Teller says you should be sharing your faith.
After one of his magic shows, he was greeting people in the crowd. There was a man waiting for him in the wings with a Gideon's New Testament. He gave Penn the Testament.
Penn graciously speaks of this experience and is complimentary to the man. But most importantly, he says something to believers about evangelism in this video.
Link to YouTube Video
Embedded video below...