Yes you are right. There are Christians in Iran. And I was wrong about folks being hung in Iran for celebrating Christmas.. oops.. Guess they do celebrate Christmas too. I am a little confused with this info I just found.. Because I know folks that are Muslim can not leave Islam without fearing for their life. So I don't understand how there can be Christian Iranians living in Iran. But it is true.. There are Iranian Christians..

Iranian Christians Celebrate Christmas in Iran

Iranian Christians celebrate the birth of Jesus Christ in a somewhat similar fashion as it is celebrated around the world. ... Christianity arrived in Iran during the Parthian dynastic period (248 BC- 224 AD). Parthian kings showed great tolerance toward other religions and Christianity gradually spread in various parts of the Persian Empire. ... The celebration of Christmas on the 25th of December is said to have originated in ancient Persia and Mithraism and has its roots in the Mithraist festival of Yalda, the celebration of the birth of Sun God, Mithra, on the eve of the first day of the winter which falls on 21st of December. http://irannewsblog.blogspot.com/200...christmas.html

Yes, Christianity sprang from Judaism I think... My understanding is that Islam did not come from Christianity.

Islam
Islam (properly called al-Islam, "submission to Allah," or God) is the name given to the religious thought system resulting from the mission of the Prophet Mohammed in Arabia in the 7th Century A.D. During his 40-year ministry, Mohammed authored the Quiran, the holy scripture of the faith. The Quiran distinguishes between submission and belief, or faith. Submission requires strict adherence to a code of righteous behavior. One who submits to the will of God is a Muslim. http://www.allfaithseminary.org/religions.asp