you can know

John 3:16 "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."

Jesus died on the cross to pay the penalty for our sin then arose on the third Day.

It says that if you believe in Him you will have everlasting life.  will you do that today?  If you do you can know you have eternal life 1 John 5:13 "These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God."