Extraordinary stories about this phenomenon keep appearing around the world lately. Many Christians want to rejoice that lost souls are being saved, but we also want to rejoice in what is true. It's not a question meant to offend. It's simply raised by millions of Christians in light of the great value that God places upon His written Word.
For valid reasons, followers of Christ throughout history have held subjective, personal stories at arm's length by comparison. After the original Apostles died and the canon of Scripture was completed, the foundation of the church was set (Eph. 2:20). Many Christians believe that visions and continuing prophecy undermine that foundation (see below). But should these "Christ vision" experiences of Muslim background believers be viewed differently? If so, on what grounds?
Read more: http://www.crosswalk.com/blogs/christian-trends/is-jesus-appearing-to-muslims-to-convert-them.html
In addition to the biblical reasons listed in the articles above, one of the reasons why I am also skeptical of these reported dreams and visions that Muslims are supposedly having about Jesus is because some of them are actually converting to the Roman Catholic Church or the Orthodox Church (both false works-righteous systems).
Another reason is because this "being" that they are encountering identifies himself, at least to some of them, as Isa. Well, from what I have researched and have come to understand is that Isa is not a name for Jesus. Isa was never a name for Jesus and is also not the Arabic translation for Jesus. Furthermore, Isa is not the Son of God. Isa never died on the cross for anyone's sins. Isa was never resurrected from the dead. Isa also hates Christians and Jews and is their destroyer. This is definitely not Jesus! (See: The Muslim Jesus, known as ‘Isa by Dr. Mark Durie - Answering Islam.)