You can know for SURE you have eternal life.

See that you are a sinner and separated from God.  For all have sinned and fall short of God's glorious standard.  Romans 3.23 (NLT)

Understand that Jesus Christ died for your sins and rose from the dead.  ...it is the Good News that saves you if you firmly believe it - that Christ died for our sins, just as the Scriptures said.  He was buried, and he was raised from the dead on the third day, as the Scriptures said.  I Corinthians 15.2-4 (NLT)

Receive God's forgiveness and grace by trusting Christ as your Savior.  Now God says He will accept us and acquit us - declare us not guilty - if we trust Jesus Christ to take away our sins.  We can be saved by coming to Christ no matter who we are or what we have been like.  Romans 3.22 (LB)

Express your desire for Christ to be the Lord of your life.  If you confess with your mouth that Jesus is Lord and believe in your heart that God raised Him from the dead, you will be saved.  Romans 10.9 (NLT)

If you're ready to be SURE, pray a sincere prayer like this:

Dear God, I am a sinner and I want Your forgiveness and hope.  I believe Jesus Christ died for my sins and arose from the dead.  I turn away from my sin and give total control of my life to Jesus Christ as my Lord.  Thank you Lord Jesus for hearing my prayer and giving me eternal life.