What assures Christians that they alone are saved?

In short, Christians believe that they are saved because Jesus told them in John 3:36, "He that believeth on the Son hath everlasting life: and he that believeth not the Son shall not see life; but the wrath of God abideth on him."

The Quran says, "We (meaning Allah) sent forth Jesus and gave Him the Gospel" in the 'Imrans 3:1-4.

In the Gospels Jesus states that God had a son (John 3:16).

The Quran states that "Those who say: 'The Lord of Mercy has begotten a son,' preach a monstrous falsehood." (Mary 19:88)

Then the Quran says "We believe in God and in what was revealed to Jesus by their Lord." (The Cow 2:135-140)

The Quran can't handle Jesus; in one breath it claims he is a prophet and an apostle, and that the Gospels were sent by God. In the next breath it says that whoever teaches that God had a son is preaching a monstrous falsehood. One can only conclude that the prophets and apostles of the Quran teach monstrous falsehoods, or that they have it wrong about Jesus and God's Son.

The profound yet simple answer to your question is contained in a speech the apostle Peter made the day after he and the apostle John were arrested and thrown into prison. The reasons were two: a) for teaching and announcing in Jesus' name the resurrection of the dead; and b) for healing in the name of Jesus a man who was born lame and had supported himself by begging outside the temple.

Peter's audience that day comprised, among others, the Jewish rulers, elders, experts in the law, the high priest Annas, the former high priest Caiaphas, and presumably many of the common people who had witnessed Peter's miraculous healing of the lame man the day before. The Jewish rulers asked Peter this question:

“By what power or by what name did you [heal the lame man]?”

Peter answered their question as follows:

“Rulers of the people and elders, if we are being examined today for a good deed done to a sick man--by what means this man was healed–-let it be known to all of you and to all the people of Israel that by the name of Jesus Christ the Nazarene whom you crucified, whom God raised from the dead, this [formerly lame] man stands before you healthy. This Jesus is the stone that was rejected by you, the builders, that has become the cornerstone. And there is salvation in no one else, for there is no other name under heaven given among people by which we must be saved” (Acts 4:8-12 NET, my emphasis).

The words I have put in boldface contain the essence of the answer to your question. The answer is a three-part answer:

1. No one besides Jesus offers salvation to humankind.

2. The name of Jesus is singularly unique in that there is no other person under heaven whose given name, Yeshua (i.e., Jesus) signifies that a.) he alone is at the same time in one person both divine and human, the Son of God and the Son of Man; and b.) he alone has the authority and the power to save people from their sins. Yeshua, in Hebrew, means "God is salvation" (see Matthew 1:21).

3. There is a "mustness" attached to the name of Jesus, since only through him can someone be saved. No one else proffers salvation to humankind.

I just used the word proffers deliberately. To offer someone salvation is one thing, but to proffer salvation to someone is another thing entirely. For a person to proffer something to another person is to offer it with only its acceptance in mind.

Many teachers, preachers, and gurus down through the centuries have offered a kind of salvation to their followers. Invariably, however, their offers have been empty and their lives have been just as messed up as their followers'--if not more so!

Jesus, however, proffers to us the only salvation that truly works, and he graciously makes it available to all who request it by faith. Moreover, he proffers it to all at great cost to himself--his very lifeblood, in fact, but at no cost to them, since salvation is a gift. All he asks is that they turn from their sin and confess him as their rescuer and Lord.

Moreover, Jesus' salvation is available to all, regardless of their socio-economic standing; their sex, age, color, nationality, or ethnicity; their prior religious affiliation or non-affiliation; or even the degree to which they have lived an ethical and moral life. Truly, the ground is level at the cross of Jesus, for all but Jesus have sinned and fallen short of God's standard of perfection. Since Jesus lived a perfect life as only the God-Man could, his sacrifice for sin was acceptable to God the Father, and the Father proved that it was so by raising Jesus from the dead!

In conclusion, becoming a Christian does make the Christian superior to anyone else who may not be a Christian. Someone has defined a Christian as simply one beggar who tells other beggars where the bread is. Jesus is that bread, and he is the only one who can satisfy the innermost spiritual hunger of the human heart.

What is salvation? What are Christians being saved from? The Apostle taught that Christians will be saved because God has promised to save all the Jews through a one sided covenant, and that, since the Greeks are to be grafted onto the vine that is Israel, Greeks will share in that covenental promise [I refrain from using the word "gentile" rather than Greek, as that an entirely different meaning then. If you are unfamiliar with this passage from Paul's writings, do a computer search in your bible software.] In other words, salvation of Christians is dependent on the fulfillment of the promise God made to Israel. If Israel is not saved neither are Christians - this is Paul speaking, of course.

Redemption of mankind through the death and resurrection of The Lord, is not the same as salvation. Redemption affects every man woman and child in the world. This idea was recently made very public by The Pope in which he said that even Atheists have been redeemed by the blood of Christ.

Neither does salvation mean going to Heaven after one dies.

So, according to Paul, it was possible to lose salvation, if Israel doesn't receive the promise God made to it. If God were to reneg on His promise to Israel, salvation would not "stick," All would be cut off from the vine, together with its root Israel.

What Paul taught was that we are adopted into the covenant, and are therefore considered to be included in "Israel." Now, this is Paul's "gospel," as he called it.

After the Church cast out all the Hebrews in the 4th. cent. (these were the children/disciples of the apostles) the Church focused on the idea that Jesus himself was the vine (Jo 15:1.) Salvation was as Jesus described in Matthew 5 in which those saved have received blessings from God - though they might not have recognized them as blessings - and the reception of all these "gifts" was the indicator that the disciple had been declared righteous by God.

The old covenant with Israel was considered by the Church to apply only to the Hebrews. And so developed the dual covenant idea [no longer a doctrine of the Church.]

So, for Christians, the reception of the virtues which are the corollary to the beatitudes, demonstrates salvation [read St. Augustines's commentary on the Beatitudes to understand this idea.] A famous Bishop has said "I was saved, I am being saved, and I hope to be saved."

So, in the "catholic" churches (Anglican, Roman, Eastern Orthodox, Greek Orthodox, Episcopal, Anglican Catholic, Anglo catholic, Church of England, and all the other branches of the catholic Church) salvation is not a certainty. We hope and we pray for the virtues of Christ, and that God will declare us righteous now, or soon, and that He sees us a being righteous at the end.

The attraction to people of modern theology is that they get salvation by accepting Jesus as their Lord. And they can't lose it - though a Baptist pastor assured me that someone who is saved cannot lose salvation, he also told me that not all his congregation was going to heaven, because not everyone was saved in the first place.

What "catholics" [see def. above.] understand is that "Christian life", as God has shown us through The Lord's demonstrations, IS salvation. And as long as we continue to live God's way, and "persevere to the end," we will keep our salvation.

The study of religious doctrines of salvation is called soteriology (the Wikipedia article is a good start). The most important part of soteriology is the theologic concept of justification.

Justification is God's cleansing of our sins and declaring us righteous. Catholics and Orthodoxs believe in justification by

• baptism (initial justification)
• avoiding sins
• the sacrament of penance if serious sin occurs (the last two form permanent justification)

Protestants believe in justification by faith alone. You can find some relevant bible quotes that can point either way on Wikipedia (after all, the reformation wars didn't come about because the bible is a clear-cut, easy to understand document).

Regarding baptism, from the Catechism of the Catholic Church:

1987 The grace of the Holy Spirit has the power to justify us, that is, to cleanse us from our sins and to communicate to us "the righteousness of God through faith in Jesus Christ" and through Baptism:

Rom 6:8-11 But if we have died with Christ, we believe that we shall also live with him. For we know that Christ being raised from the dead will never die again; death no longer has dominion over him. the death he died he died to sin, once for all, but the life he lives he lives to God. So you also must consider yourselves as dead to sin and alive to God in Christ Jesus.

Regarding penance (reconciliation), again from the Catechism of the Catholic Church:

II. Why a Sacrament of Reconciliation after Baptism?

1425 "YOU were washed, you were sanctified, you were justified in the name of the Lord Jesus Christ and in the Spirit of our God." One must appreciate the magnitude of the gift God has given us in the sacraments of Christian initiation in order to grasp the degree to which sin is excluded for him who has "put on Christ." But the apostle John also says: "If we say we have no sin, we deceive ourselves, and the truth is not in us." and the Lord himself taught us to pray: "Forgive us our trespasses," linking our forgiveness of one another's offenses to the forgiveness of our sins that God will grant us.

1426 Conversion to Christ, the new birth of Baptism, the gift of the Holy Spirit and the Body and Blood of Christ received as food have made us "holy and without blemish," just as the Church herself, the Bride of Christ, is "holy and without blemish." Nevertheless the new life received in Christian initiation has not abolished the frailty and weakness of human nature, nor the inclination to sin that tradition calls concupiscence, which remains in the baptized such that with the help of the grace of Christ they may prove themselves in the struggle of Christian life. This is the struggle of conversion directed toward holiness and eternal life to which the Lord never ceases to call us.

To quote from Bible itself, Jesus mentioned about the salvation of mankind through Him, in following verses in Bible. All these words spoken by Jesus Himself:

John 3:14-18 Just as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, so that everyone who believes in him may have eternal life.”For this is the way God loved the world: He gave his one and only Son, so that everyone who believes in him will not perish but have eternal life. For God did not send his Son into the world to condemn the world, but that the world should be saved through him. The one who believes in him is not condemned. The one who does not believe has been condemned already, because he has not believed in the name of the one and only Son of God.

John 10:9 I am the door. If anyone enters through me, he will be saved, and will come in and go out, and find pasture.

John 11:25 Jesus said to her, “I am the resurrection and the life. The one who believes in me will live even if he dies,

John 14:6 Jesus replied, “I am the way, and the truth, and the life. No one comes to the Father except through me.

Jesus talks about his death as necessary fro saving the humanity:

John 10:11 “I am the good shepherd. The good shepherd lays down his life for the sheep.

Luke: 24:46-47 and said to them, “Thus it stands written that the Christ would suffer and would rise from the dead on the third day, and repentance for the forgiveness of sins would be proclaimed in his name to all nations, beginning from Jerusalem.

Matt. – 20:28 just as the Son of Man did not come to be served but to serve, and to give his life as a ransom for many.”

Mark: 14:24 He said to them, “This is my blood, the blood of the covenant, that is poured out for many.

You're obviously familiar with the Messianic prophecies which are well expounded in Wikipedia.

The classic proof text for Christians' being saved is John 14:6 (and 10:27 below) —

Jesus said to him, “I am the way, and the truth, and the life. No one comes to the Father except through me.”

And for Jesus-as-God, there's John 10:27–30 (particularly v30) —

“My sheep hear My voice, and I know them, and they follow Me; and I give eternal life to them, and they will never perish; and no one will snatch them out of My hand.
    “My Father, who has given them to Me, is greater than all; and no one is able to snatch them out of the Father’s hand.
    “I and the Father are one.”

— and Matthew 1:23,

“Behold, the virgin shall conceive and bear a son, and they shall call his name Immanuel” (which means, God with us).

The doctrine of the Trinity [which puts Christ as God], although rooted in biblical times and supportable with quotes such as these, was only formally stated by the Early Church. But it is foreshadowed by Christ himself in John 15:26 —

“But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me.”

and at the end of Matthew's gospel, Mt 28:18—19,

And Jesus came up and spoke to them, saying, “All authority has been given to Me in heaven and on earth.
    “Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit ...”

First question to ask is what are Christians being saved from or for? Thankfully someone has saved me time from having to write that answer up (Thanks @Caleb):

What does it mean to "be saved"

Again, I would promote the necessity of relationship with God so that a follower knows the nature of God well enough to know what His desire for us. This is summed up in the famous and oft quoted verse John 3:16:

16 “For God so loved the world, that He gave His [a]only begotten Son, that whoever believes in Him shall not perish, but have eternal life.

Caleb answered what we are saved from, my last quote tells us that God does not want to lose any of us, my next part will explain the part that causes us to be in the firing line of Gods wrath.....

Rom 3:23

23 for all [a]have sinned and fall short of the glory of God,

This means we have missed the mark, we have FAILED the test, the Law we have broken. When the Law is broken justice is required. God is a just God so cannot simply ignore that we have sinned and grant mercy, otherwise He is not just. We, as humans cannot remove the need for justice, just as we cannot remove the stain of sin, any attempt to do so is futile:

Isaiah 64:6:

6 For all of us have become like one who is unclean, And all our righteous deeds are like a filthy garment; And all of us wither like a leaf, And our iniquities, like the wind, take us away.

We cannot base our idea of righteousness as the grading system that God will use, for His standards are far higher than ours.

How do you ascertain the standard of God? Would Mother Teresa make it based purely upon the standard she demonstrated? Would Hitler based upon his actions meet the requirements of Gods standards? No, surely not in the case of Hitler, but also Mother Teresa, as amazing as she was, also fell short of the requirements that would make her salvation possible.

Long story short, man cannot do anything in his own works to gain salvation. Justice IS required by and sought by God: Psalm 94

So, hopefully I have established from a Christian perspective why we are in the firing line of Gods wrath. Now to be sure of salvation in Christ as a Christian:

So, as Christians believe that it is through Christ that salvation is made possible, because our sinful ways and the requirement for justice made outside intervention a necessity, because mere man was unable to undertake this correction for themselves. Jesus was able to satisfy the demand for justice so that all that was required was for the mercy and grace of God to have a chance to win back from Satan the hearts of man.

To be sure of their salvation a Christian needs to have a relationship with God because then you are learning of His nature such as God cannot lie:

Titus 1:2

2 in the hope of eternal life, which God, who cannot lie, promised [b]long ages ago,

He loves us: John 3:16

If then, Christians agree that Paul's words are divinely inspired scripture (and remember God cannot lie) then it is plain and simple for Christians to be certain of their salvation:

Romans 10:9-10

9 [a]that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; 10 for with the heart a person believes, [b]resulting in righteousness, and with the mouth he confesses, [c]resulting in salvation.

Furthermore, a Christian believes they are being saved so they can live, but they can only live if they do not lead their live according to the flesh, but by the Spirit.

Romans 8:13

13 for if you are living according to the flesh, you [a]must die; but if by the Spirit you are putting to death the deeds of the body, you will live.

A Christian knows if they are living by the flesh because they act according to their own desire, pursuing their own agenda, but ultimately not seeking to know God more and more.

So, as a Christian, to be sure of your salvation; do not simply live to an acceptable level (i.e., the Law or to mans standards), but rather live by the Spirit.