"Can I know without a doubt that I am saved?"  "Can I know that if I were to die today that I would go to be with the Lord?"  These questions are questions that Christians have asked for years.  Is it possible to have the security of knowing that Jesus will save you with no doubts?  The best place to go for the answer is God's word, the Bible. 
     There are several passages to consider.  The first is this: "Not everyone who says to me, 'Lord, Lord' shall enter the kingdom of heaven, but he who does the will of My Father in heaven.  Many will say to me in that day, 'Lord, Lord, have we not prophesied in Your name, cast out demons in your name, and done many wonders in Your name?'  And then I will declare to them, 'I never knew you; depart from Me, you who practice lawlessness.' (Matthew 7:21-23).  -and-  "There is none righteous, no, not one;" (Romans 3:10) -and-  "for all have sinned and fall short of the glory of God" (Romans 3:23).
     There is not one person who has not fallen short of God's expectations.  All have sinned. Therefore, we cannot get to heaven on our own merit.  Also, close examination of the words of Jesus reveals that doing good things in the name of God is not enough.  God requires full and complete obedience.  Sadly, many fall into the category of thinking they will get into heaven because they are "good people".  Jesus says that Heaven is for those who do "the will of My Father in heaven".  Now, if this were the extent of the Biblical message, it would be bad news.
     However, the Bible contains good news:  "There is therefore now no condemnation to those who are in Christ Jesus..." (Romans 8:1).  -and-  "But if we walk in the light as He is in the light, we have fellowship with one another, and the blood of Jesus Christ His Son cleanses us from all sin.  If we say we have no sin, we deceive ourselves, and the truth is not in us.  If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness."  (I John 1:7-9)  -and-  "My little children, these things I write to you, that you may not sin.  And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous.  And He Himself is the atoning sacrifice for our sins, and not for ours only, but also for the whole world."  (I John 2:1-2).
     For those who have put their faith in Jesus as their Lord and Savior, having repented and been baptized into him (Galatians 3:26-27; I Peter 3:21), they now have Christ.  There is now no condemnation because they are IN Christ.  The blood of Christ has washed their sins away and they are no longer condemned because of it.  If you walk in the light, the blood of Jesus cleanses your sins.  The ideal is to NOT SIN, but if you do, Jesus is your advocate (one who speaks or pleads your case) to the Father and the sacrifice for your sins.
     Remember, the ideal is not to sin, but God has made a contingency plan - in Jesus we have forgiveness.  This does not mean we take a flippant attitude about sin (Romans 6:1), but that we are not condemned when we stumble.
     The key is lifestyle:  "And you know that He was manifested to take away our sins, and in Him there is no sin.  Whoever abides in him does not practice sin...He who practices righteousness is righteous..." (I John 3:5-7).  If you practice sin even though you have become a "Christian", you're lost (I John 3:8).  You have had your sins washed away and live a changed life (Colossians 3).  You no longer "practice" sin.  You may stumble, but if you repent and confess, your sins will be forgiven.  The result is confidence and security.  Christians can confidently look forward to the day of the Lord (2 Peter 3:11-13).  "These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life..." (I John 5:13).  Yes, you can know if you have eternal life.  Read and practice the word of God.
     The Bible does not teach "once saved, always saved."  A person after finding Christ can become lost again (Galatians 5:4; Hebrews 6:4-6).  However, as we have just seen, the Bible doesn't teach "once saved, barely saved" either.  Praise God!