You mean...I CAN know for sure?
YES!

HERE'S HOW...

REALIZE AND ACKNOWLEDGE:
"For all have sinned, and come short of the glory of God"
Romans 3:23

REALIZE AND ACKNOWLEDGE:
"...Christ died for our sins..."
I Corinthians 15:3

REALIZE AND ACKNOWLEDGE:
"For the wages of sin is death..."
Romans 6:23

REALIZE AND ACKNOWLEDGE:
"...but the gift of God is eternal life through Jesus Christ our Lord."
Romans 6:23

REALIZE AND ACKNOWLEDGE:
"That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God
hath raised him from the dead, thou shalt be saved."
Romans 10:9

WHY NOT PRAY THIS PRAYER FROM THE HEART RIGHT NOW?
"Dear Lord Jesus,
I believe God raised You from the dead to save me from my sins.  Please be the Master of my life.
Come into my heart and save me right now.
Thank you for saving my soul.
Amen."