Do Islam and Christianity have different origins?

In a Nutshell:  Islam and Christianity originate from God. This is apparent in the manner by which God chose to send his revelation and the overarching message itself. Origins of Christianity and Islam The origins of Christianity and Islam can be traced back to God. Both religions originate from the Middle East and both are monotheistic and messengership is the method by which God communicates with mankind in both. The overarching narrative about God as the creator of man, life and the universe, and the purpose of this life to do good and be rewarded with Heaven in the next life, or do evil and be punished in Hell is the central message in both Christianity and Islam. Messengers The manner in which God chose to communicate His revelation to mankind in both cases has been through the selection of a man to proclaim His message to others. In Christianity the man chosen by God to deliver His message was Jesus(as), and later for the propagation of Islam God chose Muhammad (saw). " I will raise up for them a prophet like you from among their brothers. I will put my words in his mouth, and he will tell them everything I command him." [Deuteronomy 18:18] "Muhammad is not the father of any of your men, but he is the Messenger of Allah and the seal of the prophets and Allah has full knowledge over all things" [Al-Ahzab 33:41] The two verses above show that in both cases God chose the man who would become His messenger. In fact, in the biblical verse God also gives glad tidings of another prophet to come after Jesus(as) "I will raise up for them a prophet like you from among their brothers" This reference to another prophet after Jesus is thought to be the Prophet Muhammad(pbuh). Furthermore, God affirms in the Quran that Jesus(as) was given the glad tidings of a messenger to come after him by the name of Ahmad which is another name for Muhammad. "And [mention] when Jesus, the son of Mary, said, "O children of Israel, indeed I am the messenger of Allah to you confirming what came before me of the Torah and bringing good tidings of a messenger to come after me, whose name is Ahmad." But when he came to them with clear evidences, they said, "This is obvious magic.""[As-Saff 61:6] These evidences prove that the source of the Quran and the Bible is one and the same - God. Miracles In both religions God gave his messengers a miracle so that they could prove to their people that they were speaking the truth. Jesus was given the miracle of bringing the dead back to life. It was an extraordinary event beyond the powers of any man offered as proof that he was a messenger of God. Similarly, Muhammed (pbuh) also had a miracle which proved that he was a messenger. His miracle was the Quran itself. The Quran contains a challenge directly from God to the whole of mankind highlighting its miraculous nature: "And if you all are in doubt about what I have revealed to My servant, bring a single chapter like it, and call your witnesses besides God if you are truthful." (Al-Baqarah 2:23) The inimitability of the Quran makes it a miracle that transcends time and place, and taken in conjunction with the verse stated earlier where God reveals that Muhammad is the seal of the prophets ie. the last prophet, this miraculous Quran allows mankind to be guided to the truth without the need for further messengers as the message has become irrefutable and incorruptible. A beacon of light for those who are sincere about seeking the truth. A Common Narrative The Islamic tradition and Christianity share common stories. God created Adam and Eve. They worshipped God and He told them not to eat the fruit from the tree. The Bible notes: "From any tree of the garden you may eat freely; but from the tree of the knowledge of good and evil you shall not eat, for in the day that you eat from it you will surely die." Genesis 2: 16-17 The Quran comments: "And We said, O' Adam, dwell – you and your wife – in the Garden and eat freely of its (fruits) as you wish, but do not come near this tree lest you become wrongdoers'". (Chapter 2, Verse 35)  Allah (swt) also told Adam (pbuh) to beware of Satan: "And We said, 'Surely this one is an enemy to you and your wife, so do not let him drive you out from the Garden, so that you are made miserable'". (Chapter 20, Verse 117) Satan mislead them and they disobeyed God by eating the fruit and as punishment were sent to the Earth. On Earth they continued to worship God. Adam had children who in turn had children and over the generations formed into many tribes. As time went by the people started to associate and worship others besides God, so He sent to them a man from amongst themselves to remind them and guide them back to the worship of one God. Men chosen by God to guide people back to the worship of one God are called  messengers or prophets of God, and history bears witness to a long line of such people: Noah, Moses, Abraham, Ishmael, Isaac, Jacob, Joseph, Jesus and Mohammed to name but a few. Not only the story of Adam but the story of Joseph, Moses and Jesus are also similar. The stories are similar because they originate from the same storyteller. Interestingly, God only succeeded the previous message with another message when the former had been corrupted by the people; hence, the corruption of the message as relayed by Jesus led to the coming of the Prophet Muhammad who affirmed the previous prophets: "Say: We Believe in God and what has been revealed to us, and what was revealed to Abraham and Ishmael and Isaac and Jacob and the tribes, and what was given to Moses and Jesus and to the prophets from their Lord; we do not make any distinction between any of them, and to Him (God) do we wholly give ourselves." (Qur'an 3:84) Jesus (as) and Muhammad (saw) had the same message worship one God and only him. In both cases God sent the angel Gabriel and in both cases each prophet affirmed those who came before them and then proceeded to preach the revelation given to them. The "bad guy" in both cases is Satan, and they both talk about life after death, the day of judgment and Heaven and Hell. Conclusion In conclusion, both religions originated from the same source because they follow a pattern of messengership and miracles, monotheism is a central theme and they convey the same story of Heaven and Hell, reward and punishment, angels and satan not to mention that each new revelation confirms that which came before it. This proves the source is the same. The source is God.