How does one know that he or she is saved?  How can one be sure?

First, what is salvation?  The Holman Bible Dictionary defines salvation as:
"The acts of snatching someone from the perils of death.  Scripture extends the definition of salvation to the deliverance from the penalty and the power of sin."

Hebrews 2:1-3
"Therefore we must give the more earnest heed to the things we have heard, lest we drift away.  For if the word spoken through angels proved steadfast, and every transgression and disobedience received a just reward, how shall we escape if we neglect so great a salvation, which at the first began to be spoken by the Lord, and was confirmed to us by those who heard Him."

Redemption, which is closely related to salvation, is defined as:
"The purchase back of something that had been lost by the payment of a ransom.  That ransom is the payment made for our redemption.  The debt against us is not viewed as simply cancelled, but is fully paid.  Christ's blood or life, which He surrendered for them, is the 'ransom' by which the deliverance of His people from the servitude of sin and from its penal consequences is secured.  (1 Corinthians 6:19-20; Galatians 3:13; Ephesians 1:7 and many others)

Also tied together with salvation and redemption is regeneration:
"This word is found only in Matthew 19:28 and Titus 3:5.  It literally means "a new birth".  It denotes a change of heart that is elsewhere spoken of as passing from death to life (1 Jon 3:14); becoming a new creature in Christ (2 Corinthians 5:17); being born again (John 3:5); a renewal of the mind (Romans 12:2); a resurrection from the dead (Ephesians 2:6); a being quickened (Ephesians 2:1, 5).  This change is ascribed solely to the Holy Spirit.  It originates not with man, but with God (John 1:12-13; 1 John 2:29; 1 John 5:1, 4)  As to the nature of the change, it consists in the implanting of a new principle or disposition in the soul; the impartation of spiritual life to those who are by nature 'dead in trespasses and sins'.  The necessity of such a change is emphatically affirmed in the Scriputres (John 3:3; Romans 7:18; Romans 8:7-9; 1 Corinthians 2:14; Ephesians 2:1; Ephesians 4:21-24)."

So, what are the elements of salvation, or being saved?

In John 3:3, Jesus said to Nicodemus: "Most assuredly, I say to you, unless one is born again he cannot see the kingdom of God."  Jesus goes on to say in John 3:5 "Most assuredly, I say to you, unless one is born of water and Spirit, he cannot enter the Kingdom of God."

In John 3:16-17 Jesus says "For God so loved the world that He gave His only begotten Son, that whoever believes in Him should not perish but have everlasting life. For God did not send His Son into the world to condemn the world, but that the world through Him might be saved."

In Matthew 4:17 it says "From that time Jesus began to preach and to say 'Repent, for the kingdom of heaven is at hand'."

(Repentance is a turning away from sin and a turning to God.  It is hating the things that God hates.  It involves a change of mind and a change of heart).

In Matthew 28:18-20 it says "And Jesus came 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 of the Son and of the Holy Spirit, teaching them to observe all things that I have commanded you."

In 1 John 1:9, John says "If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness."

In summary, these are the basic elements of Biblical salvation:

• Being born again - regenerated - a new heart and a new mind
• Confession of sin - agreeing with God that we are sinners in need of a Savior
• Repentance - turning from sin and turning to God
• Belief in the finished work of Jesus Christ on the cross - the Gospel (1 Corinthians 15:3-4)
• Obedience to all the commands of Jesus Christ (the entire Word of God)

All too often today I hear someone say that they are saved because they said a prayer and asked Jesus into thier heart.  This is un-Biblical, and borders on heresy.  No place in the Bible does it say that we are saved by saying a prayer and asking Jesus into our hearts.

This generally comes from a misunderstanding and gross mis-application of a verse in Revelation.

Revelation 3:20  "Behold, I stand at the door and knock.  If anyone hears My voice and opens the door, I will come in to him and dine with him, and he with Me."

To use this verse as an evangelistic tool is to take this verse way out of context.  This is Jesus speaking to the church at Laodicea, the apostate church of the day, and representative of the apostate church today.  He is speaking to a church who has fallen away from the faith - apostates.  He is telling them, as individuals (not corporately) that if they repent and return to Him, they will save their soul.  Those who don't will perish.

Biblical salvation is, first and foremost, the work of the Holy Spirit.  The Holy Spirit so works in a person's life as to make that person aware of his or her sinful condition and thier need for a Savior.  Only then can there be true repentance from sin, a true born-again condition where we are made a new creation, an acceptance and belief in the Gospel, and a desire to follow Jesus Christ and be obedient to Him.

There are far too many "professing Christians" today who think they are saved but are not.  This is a tragedy, and the bigger tragedy is that the leadership in the "Christian" church is not making them aware of their lost condition.

Everyone needs to do as Paul admonishes:  "Examine yourselves as to whether you are in the faith.  Test yourselves.  Do you not know yourselves, that Jesus Christ is in you?  - unless indeed you are disqualified".  (2 Corithians 13:5)