It is sadly true that some equate “fundamentalist Christianity” and “fundamentalist Islam.” But that’s for a later blog. Here I write regarding the perception these two religions are basically the same except for what we believe about Jesus.
There are many differences between Christianity and Islam. To say they are the same except for one point is a statement of ignorance. For example, in the past three centuries, Christianity has promoted peace all over the world. Amy Orr-Ewing points out the dissimilar nature of Islam. “I could not agree that ‘peaceful’ was a good adjective to describe the religion as a whole either historically or in the present day.” 
But for the sake of argument let’s suppose what this boy’s view is true. There is only one difference. Our belief about who Jesus is.
Let me say, that if our belief about Christ is the only difference, that is a monumental difference! That one issue makes Islam and Christianity diametrically different.
Foundation of Christianity
“For what I received I passed on to you as of first importance, that Christ died for our sins according to the Scriptures; that he was buried, that he was raised on the third day according to the Scriptures: And that he appeared to Peter, … and last of all he appeared to me also …” 
Paul cites this gospel as “of first importance”. Jesus Christ actually died for our sins and His death was verified by the fact that He was buried. What is more, He was raised to life again, and appeared to many, including Paul. On these statements of first importance, our Islamic friends disagree.
They might say it this way. “Christ fainted on the cross and was temporarily placed in a tomb. Later he revived and he and his disciples duped the world into believing that he had been raised from the dead.” In the Koran Jesus is held to be a major prophet, although less than Muhammad. Muslims believe Christians are deceived and the New Testament is in error about what happened.
Paul’s version of events, written 700 years earlier than the Koran, is the bedrock of Christianity. This point “of first importance” is the all of the Christian faith.
Paul wrote that if the gospel facts are not true, as Muslims contend, then our whole religion is vain. “If only for this life we have hope in Christ, we are to be pitied more than all men.” 
So even if this one point is the only difference between Islam and Christianity, which it is not, it is a massive difference that forever prohibits these two faiths from agreement.
Ravi Zacharias closes this blog with a pertinent comment.“One of India’s leading “saints,” Sri Ramakrishna, is said to have been for a little while a Muslim, for a little while a Christian, and then finally, a Hindu again, because he came to the conclusion that they are all the same. If they are all the same, why did he revert to Hinduism? It is just not true that all religions are the same." 
 Amy Orr-Ewing, Beyond Opinion, Ravi Zacharias, Editor and Author (Nashville: Thomas Nelson Inc., 2007) 13
 1 Corinthians 15:3-5 & 8 (New International Version)
 1 Corinthians 15:19 (New International Version)
 Ravi Zacharias, Jesus Among Other Gods (Nashville: Thomas Nelson Publishers, 2000) 158