In 1 John 5:13, John says he wrote to believers so that they may know they have what?

Answer: Eternal life

John wrote to those who believe in the name of the Son of God so that they may know that they have eternal life.

“I have written these things to you who believe in the name of the Son of God, so that you may know that you have eternal life.”— 1 John 5:13 (BSB)