People can be transformed. The opponents of the Prophet (p) were particularly vicious against Muslims. Hind actually bit into the liver of the Prophet's uncle, Hamzah, when he was martyred at the Battle of Uhud. However, she later became a Muslim, and hence became a Companion of the Prophet (p), a member of that special generation of humanity. In fact, she even narrated hadith which can be found in the well-known compilations. Repentance is a recourse that the Lord of the World's has given humanity. [p129, Purification of the Heart by Hamza Yusuf]
Christians having dreams and converting to Islam:
Invitation to Islam
Jesus taught people to do the Will of God (according to Mark 3:35) in order to become his brothers, mothers or sisters. A Muslim means one who submits to the Will of God. Do you want to become a brother/sister of Jesus? If yes, become a Muslim.
Learn about Islam: