I already answered this. I guess you just missed it.
But anywho, the Bible says that the person who has no fear of the return of Christ is the person who looks like Jesus in this life. And it isn't a numerical number. It's if you are growing up into the qualities of the Spirit in increasing measure-2 Peter 2:5-11.
If you're not growing up into the image of Christ and are stagnate in your old lawless, immoral, disobedient life you can't be sure if you're saved and ready for when Jesus comes back. Only those growing up in Christ according to the qualities of the Spirit have that sureness of their salvation. That's why we're told to work, so we can have that sureness, and get saved for real if we can't produce the works of faith that show a person is saved. Remember, unbelievers can't do that. They can call themselves saved all day long, and believe it, but that doesn't make it so. Only the Spirit working in our lives growing us up into the image of Christ testifies to us having truly received Christ in salvation.