My wife and I stayed with a couple last night and she is German, her husband is in the service and headed to Afghanistan  and her father is from Tunisia and a Muslim. She is not a Muslim. they are both unbelievers but we shared some with them last night of our faith and praying the Lord opens their hearts soon.. She said that with Muslims they don't really care if you say you are a Christian but once you are baptized  they cut you off and you are shunned..and persecuted. I have heard reports of the same in the Hindu world as well. A friend's daughter and husband are missionaries in India.  Baptism is definitely a sign of separation from the world and being joined to Jesus in his death burial and resurrection. it is a statement to the world and principalities and powers of the reality of your faith and belief.  Furthermore, I can't find any  biblical evidence of  any believers in the book of Acts being baptized  but in the name of Jesus..  A lot of peoples and churches nowadays don't put a lot of  emphasis on water baptism but evidently the unbelievers do and apostles and disciples did.  
Growing in grace and knowledge of the Lord Jesus Christ
Blessings!
Keith T