I'll be laying out things I've found that show that radical Muslims don't even get "their own" Religion:

Muslims claim that God is singular:

Bible:
In the begining, God said, "Let us make man in our image, after our likeness:",
which , inpart could account for the eventual Trinity.

Qur'an:
In support of this in the Qur'an, which is contradicted by muslim teaching is;
  (002:034): "And behold, We said to the angels: "Bow down to Adam" and they bowed down. Not so Iblis(satan): he refused and was haughty: He was of those who reject Faith.".
  (003:055): "Behold! Allah said: "O Jesus! I will take thee and raise thee to Myself and clear thee".
Islam refuses to acknowledge that God is not singular and that Jesus was, is a part of God. They go as far as to use this as a reason to kill non-muslims, but their own writtings support the "We" pretext and that God raised Jesus upto himself.

Muslims insist that Jesus was "only" a prophet, but their own book says;

Qur'an:
 (003:045): "Behold! the angels said: "O Mary! Allah giveth thee glad tidings of a Word from Him: his name will be Christ Jesus, the son of Mary, held in honour in this world and the Hereafter and of (the company of) those nearest to Allah;
  (003:047): "She said: "O my Lord! How shall I have a son when no man hath touched me?" He said: "Even so: Allah createth what He willeth: When He hath decreed a plan, He but saith to it, 'Be,' and it is!"
  (003:049): "And (appoint him) a messenger to the Children of Israel, (with this message): "'I have come to you, with a Sign from your Lord, in that I make for you out of clay, as it were, the figure of a bird, and breathe into it, and it becomes a bird by Allah's leave: And I heal those born blind, and the lepers, and I quicken the dead, by Allah's leave; and I declare to you what ye eat, and what ye store in your houses. Surely therein is a Sign for you if ye did believe;
  (003:055): "Behold! Allah said: "O Jesus! I will take thee and raise thee to Myself and clear thee (of the falsehoods) of those who blaspheme; I will make those who follow thee superior to those who reject faith, to the Day of Resurrection: Then shall ye all return unto me, and I will judge between you of the matters wherein ye dispute.

Virgin Birth, Christ Jesus... "held in honour in this world and the Hereafter and of those nearest to Allah" (God) then he (Jesus, son of God) created life from clay and his own breath from Allah (God) and finally God is to raise Jesus upto himself (Equal) and those who follow Jesus (Christians) will be made Superior to those who reject.

I believe the reason Extremist Muslims berate Jesus is to try and give undo credence to Muhammad. They try to put him (Muhammad) on the same level as that of
Jesus Christ, the only begotten Son of God.

I can go on for a long time and will, but at this time I need to get to coding for pay.