In Islam it is not possible to know God, nor to have a relationship with God. Regarding Islam vs Christianity, the Islam believers are subject to an overseer, like that of slaves. As for Christianity, we all know about the free gift of salvation, which is what really matters…and we owe it all to Jesus our Lord and Savior.
Many people incorrectly believe the Bible and Qur’an are similar in the sense they both let you know God. This is not true. The Bible is the “Word of God” and allows you to know God. The God of the Qur’an does not allow you to know him. In true Islam Allah is unknowable. In fact, it is heresy in Islam to claim to be able to understand and know Allah. In Islam, such people are called “Sufis” and are often branded as heretics.
The Qur’an teaches that Allah did not, would not, and will not die for you, nor would he send any “helper” to die in your place. We see this in Qur’an 4:52 “Those are they whom Allah has cursed, and he whom Allah has cursed, thou, O Mohammad, will find for him no helper.” And we see the same in Qur’an 3:152 “Our Lord, indeed whoever You admit to the Fire – You have disgraced him, and for the wrongdoers there are no helpers.”
In fact, the Qur’an teaches that Jesus did not die on the cross, but was taken up into heaven, and Judas was crucified in His place. Further, the Qur’an teaches that there is no need for God to provide a sacrifice for sin because ignorance of Islam, not sin, is man’s problem.