The answer to this question could have an infinite number of reasons. Here are several of them:
A. Ignorance
Some Christians haven’t fully understood God’s sovereign operation of securing our salvation forever. They tend to base assurance on feeling and don’t understand the objective truth of God’s Word on this issue.

B. Temptation
Christians feel the pull of the flesh to sin even though they have a new nature. This pull is disconcerting.

C. Uncertainty
Christians who were saved at a very young age often can’t remember the “experience” of the conversion moment. Link that with the “glowing” testimonies of
people saved out of a life of wickedness and you have a formula for doubts. The “flash” of the dramatically changed life can cause others to doubt their own salvation.

D. Trials
Some Christians become spiritually unstable because they can’t see the hand of God in all their trials. “How could God love me and let me go through this?”

E. Disobedience
Perhaps the most common reason for lacking assurance is disobedience. With disobedience comes guilt, and then we question “How could I possibly be saved and have done, ”

God help us

WHAT BRINGS ASSURANCE OF SALVATION INTO MY LIFE?
It is possible you may have doubts from time to time. Just remember that Satan is a liar (John 8:44), and his first recorded words in the Bible were casting doubt upon God’s Word (Genesis 3:1). Here are some ways you can have assurance, or deepen your assurance in what God has done for you:
A. Learn the Word of God.
Your salvation is based upon what God has said — not upon how you think or feel. Thus it is important for you to read and study the Bible. Read 2 Timothy 3:14,15.

B. Thank God for His gift of salvation.
According to Romans 6:23, you have received the GIFT of E__ __ __ __ __ __ L__ __ __ . Have you thanked God for this gift yet? Thanksgiving is evidence of faith. Read 2 Corinthians 9:15.

C. Make a public testimony before others.
Have you told someone that you have trusted the Lord Jesus Christ? Look at 1 John 4:15 and see the relationship between confessing Christ and assurance. Read Matthew 10:32 and Romans 10:9,10. One way you can confess Christ publicly is to come forward at the “invitation” in one of our Church services. The pastor will gladly introduce you to the Church.

D. Attend church services faithfully.
Fellowshipping with your brothers and sisters in Christ will encourage you. Many of them have experienced the same doubts you may have. Hebrews 10:25 commands this, while Hebrews 10:22 talks about assurance. Have a goal to begin attending all the services.

E. Live a righteous life.
Sometimes a full assurance does not come until God sees we mean business for Him. According to Isaiah 32:17, the effect of
R__ __ __ __ __ __ __ __ __ __ __ __ is quietness and A__ __ __ __ __ __ __ __ forever. Remember, your peace and assurance is based upon believing God’s promises and not on your feelings.
· Don’t sugarcoat sin in your life! Recognize it, hate it, call it for what it is – rebellion against God.