One thing Christianity and Islam have in common is the exclusivity of heaven. Both teach that people must confess key doctrines of their faith to go to heaven. Since the salvation doctrines of Christianity and Islam are contradictory, both cannot both be true.
There are three considerations for Muslims regarding heaven according to Islam. First, Muslims can go straight to heaven if they are martyred in jihad (meaning struggle or holy war).
“You who believe, shall I show you a bargain that will save you from painful punishment? Have faith in God and His Messenger and struggle [jihad] for His cause with your possessions and your persons—that is better for you, if only you knew – and He will forgive your sins, admit you into Gardens graced with flowing streams, into pleasant dwellings in the Gardens of Eternity. That is the supreme triumph” (61:10).
Second, Muslims who are not martyred in jihad can expect to spend time in hell.
“Not one of you but will pass over it [hell]: this is, with thy Lord, a Decree which must be accomplished. But We shall save those who guarded against evil, and We shall leave the wrong-doers therein, (humbled) to their knees” (Quran 19:71-72).
Third, even though the previous passage states “We [Allah] shall save those who guarded against evil,” there is no way for a Muslim to know they have done this to Allah’s satisfaction. Even Muhammad was not sure of his salvation. Muhammad recited, “I do not know what will be done to me or to you” (46:9). Therefore, Muslim’s have no certainity they will go to heaven.
The key consideration for Christians regarding heaven is faith in Christ.
“… if you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved” (Romans 10:9).
In Christianity, it is the martyrdom of Christ, not a believer, that assures heaven.
“In Him [Jesus] we have redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace” (Ephesians 1:7).
In Christianity, believers are not condemned to hell for a time.
“There is therefore now no condemnation for those who are in Christ Jesus” (Romans 8:1).
Instead, Christians are promised heaven.
“For the wages of sin is death, but the free gift of God is eternal life in Christ Jesus our Lord” (Romans 6:23).
Christians are saved by the effort of Christ, not their own.
“For by grace you have been saved through faith. And this is not your own doing; it is the gift of God, not a result of works, so that no one may boast” (Ephesians 2:8-9).
Christians have the promise and assurance of salvation.
“I write these things to you who believe in the name of the Son of God that you may know that you have eternal life” (1 John 5:13).
Jesus knew where he was going and where believers will go as well.
“In my Father’s house are many rooms. If it were not so, would I have told you that I go to prepare a place for you?b And if I go and prepare a place for you, I will come again and will take you to myself, that where I am you may be also” (John 14:2-3).
Both faiths are in agreement that to worship a false god will prevent such people from entering heaven. Jesus stated, “…I am the way, and the truth, and the life. No one comes to the Father except through me” (John 14:6). This is because only Jesus paid the penalty for sins on the cross and overcame death through His resurrection. Based on Jesus’ words, it is not possible to get to heaven through Islam.