Christianity insists that man is fallen, that we are "dead in our sins" and that we are in fact incapable of standing up to a holy and righteous God.
Islam, on the other hand, says that humankind is weak and forgetful but not fallen. Islam teaches that man is capable of righteousness—all he has to do is just do it. This marks a defining difference between Islam and Christianity. The difference has far-reaching implications.
First, examine the evidence. All of history is a testimony to the sinfulness of man. Let’s be honest, in examining ourselves, we often only do good if it suits our mood, feeds our ego or fulfills an agenda. We certainly do not always love God above everything else, nor love our neighbor as ourselves. None of us keeps all of the Ten Commandments all the time. Parents do not need to teach a child to be bad (selfish or mean); it comes quite naturally to all humans. Everyone has a conscience, and if we are honest we must acknowledge how far short we fall of God's perfect standard. As a result, we must face the reality that we fall far short of standing upright before a Holy God.
The Bible says that whoever stumbles at just one point of the law is guilty of breaking all of it (James 2:10). Consider this example... An agnostic person considers himself to be a moral person, therefore expressing doubt about sinfulness. When asked this question, "If someone goes into a store a hundred times without stealing anything, but one time does steal something, is he guilty or innocent?" "Guilty!" the agnostic exclaims.
So it is. We are all guilty and deserve punishment. But we are not just guilty once. We are all guilty all the time!
We never have perfect love, justice, or acceptance. We often live as if God does not matter. Our faith is continually subject to wavering. We constantly are inclined to trust ourselves rather than God. We are always subject to feelings of revenge, lust, hatred, jealousy, and covetousness. Selfishness dominates our daily lives. We stubbornly deny truth in favor of what we wish were true.
Hypocrisy is such an obvious problem that it is a common complaint toward even religious people. Our narrow-minded attitude is a perpetual trap for prejudice and indifference. While we are perhaps not as bad as we could be, sin touches every aspect of our lives. Sin is exceedingly corrupting.
Interestingly, while Muslim doctrine denies man's sinful nature, the Quran agrees with Christian doctrine at least in one place, Sura 12:53: "And I call not myself sinless; surely [man's] self is wont to command evil, except those on whom my Lord has mercy." It sounds an awfully like the Bible, but Muslims seem to put no weight on this passage. Instead, they insist that Muslims naturally gravitate toward the good.
Jerry Rassmamni, author of From Jihad to Jesus, asks, "If Islam gravitates toward good, as the Muslims claim, then why is it that in Pakistan, a Muslim country of 140 million, only one million file their tax returns annually? Why are the 'basically good' tax evaders prodding Pakistan's government into near bankruptcy and depriving Pakistan's poor of basic government programs? And why do the majority of refugees in the world spill out of Muslim countries? The perceived goodness of Muslims is an illusion."
In addition to its theological implications, the variant views on the nature of man have significant sociopolitical implications. As expressed by the late Chuck Colson of Prison Fellowship ministries who said... "The Islamic worldview denies the sinfulness of man, which gives rise to utopian visions: If man is corrupted by society, then those who come to power can create the perfect society by strictly enforcing Islamic law."
Ironically, the Muslim view of man is not unlike communism, which is based on the notion that man is basically good, or at least can be perfected by government. But nation states based on such utopian concepts have always been failures and are particularly oppressive to its citizens.
The difference between Islam and Christianity on the nature of man is not trivial. If Christianity is correct on this point, the practices of Muslims are futile because their efforts will not get them a right standing before the True God.
Only an acceptance of Christ's finished work of the cross [sacrifice] as a substitutionary payment for humanities sins will get anyone into a relationship with God. If Islam is correct, the whole purpose of Jesus' sacrificial death and resurrection was a worthless scam.
The nature of man, man’s sin, brings us to the matter of Salvation. Islam, from the Biblical–Christian perspective, has an incomplete view of both the holiness of God and the sinfulness of mankind.
Given man's sinful nature and the gap it creates between us and a holy God, Christianity teaches that man cannot earn salvation. Nor can God just wink at sin. We need a savior who will bridge the gap and who will pay the penalty for us. Salvation is only in Christ's finished work on the cross and our subsequent acceptance of His Plan of Salvation (Acts 2:38) that God considers our blemishes healed. This is what Christianity is all about... restoration of our relationship to the Holy God.
As it says in the Bible, in the sight of a Holy God all of us have become like one who is unclean, and all our righteous acts are like filthy rags (Isaiah 64:5-7). But God demonstrated his love for us in this: While we were still sinners, Christ died for us (Romans 5:8). That is good news indeed.
But Islam denies all of this. It even denies that Jesus died on the cross at all (Sura 4:157) this in spite of overwhelming evidence both from the Bible and from historical sources outside the Bible. It denies that Jesus conquered death by his bodily resurrection, an historical event acknowledged by rigorous critical scholarship. Islam must deny these things because their religion is based on the idea that you can earn your way to heaven.
Christianity teaches that our salvation is a free gift through faith alone in Jesus Christ and specifically “not by works” (Ephesians 2:8-9; Romans 4:1-3; Titus 3:5-7; 1 Corinthians 1:29). Islam teaches that one gains entrance into heaven by ones works in addition to faith (but not faith in Christ). These are clearly opposing positions.
Christianity insists that belief in Christ is the only way to heaven. Rejection of Christ dooms us to the eternal punishment we deserve as rebellious sinners. (Mark 16:16; John 3:16-18, 36; John 10:7-10; John 12:48; John 14:6; Acts 4:12; Galatians 1:6-9; Philippians 2:9-11; 2 Thessalonians 1:8-10; 1 Timothy 2:5; 2 Peter 2:1; 1 John 2:22-23; 1 John 5:12-13.) While this may seem unfair in one sense, in another sense it is the ultimate in fairness. God provided a way for sinful man, who otherwise falls helplessly short, to be forgiven and to come into communion with Him!
Because the Christian doctrine of salvation through Christ alone so often draws accusations of intolerance from non-Christians, it may be helpful to say a bit more about it. One thing that this doctrine does not say, is that those who have never heard of Christ are automatically doomed. It is also clear that it is not Christians who can judge, but only God. God alone can know the heart of each individual. God loves everyone, including non-Christians, and he wants everyone to come to the knowledge of a saving faith (1 Timothy 2:4). But it also clear through this doctrine that anyone who consciously rejects Christ is rejecting God's offer of reconciliation. In this case, one gets what he wants, an eternity without God.
Islam is equally exclusive in its claims, as it teaches that only Muslims will go to heaven (Bukhari 4:297). Islam similarly insists that anyone who rejects their Allah and his apostle (that is, Muhammad) is condemned to hell. So, again, the two religions are at loggerheads.
While Christians believe that salvation is assured through faith and faithful living, Muslims never have assurance of salvation (except probably through martyrdom in a jihad—Sura 9:20-22). Islam teaches that at the end of your life, Allah weighs your good works against your bad works on a scale. In general, if your good works are adequate, you get to heaven (Sura 23:103). But even then it is not assured because Allah can let anyone in he chooses (Sura 9:15, 27). Muhammad himself expressed doubts about his own salvation (Bukhari 5:266, 9:131).
Man is sinful. As put by Jerry Rassamni, author of From Jihad to Jesus, "Although the [Islamic] law is verbose and enslaving, it is powerless to justify a person before the Almighty. No matter how many times a beast washes in the river, it remains a beast, and no matter how long a log soaks in the water, it will never become a crocodile. In the same manner, no matter what humankind does in its own strength, they remain sinners in the sight of a holy God."
Only Christianity offers a solution. God sent his only son Jesus to live the perfect life for us, and to suffer the punishment for man's sin. There had to be a sacrifice... punishment for sins in some way, even though mankind proved his inability to satisfy God's demands adequately. In this way God reconciled his demands for obedience while exercising his mercy toward sinful men. Only the Messiah, whom even the Quran called perfect (Surah 19:19) is righteous enough to take away the sin of the world.
For God so loved the world that he gave his one and only son—that whoever believes in him shall not perish but have everlasting life (John 3:16).
Whoever believes in the Son has eternal life; and he who does not believe the Son will not see life, but the wrath of God remains on him (John 3:36).
Muslims must be willing to ask themselves... How do you deal with your guilt? Through our conscience and the law we all know we are guilty before God. Do you really think that your Five Pillars will be sufficient before an all-powerful God to get you to eternal life? External obedience to the law does not make a person spiritually clean.
If the Bible is correct, the only conclusion is that belief in the teachings of Islam does not lead to eternal life but to rejection by God and eternal damnation for all adherents of Islam.